450 lines
18 KiB
Diff
450 lines
18 KiB
Diff
1. Added "$(objpfx)tst-cmsghdr: $(libdl)" to socket/Makefile since we still
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need $(libdl) in RHEL8.
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2. Included stddef.h in socket/tst-cmsghdr-skeleton.c because it uses NULL.
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commit 9c443ac4559a47ed99859bd80d14dc4b6dd220a1
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Author: Arjun Shankar <arjun@redhat.com>
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Date: Tue Aug 2 11:10:25 2022 +0200
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socket: Check lengths before advancing pointer in CMSG_NXTHDR
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The inline and library functions that the CMSG_NXTHDR macro may expand
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to increment the pointer to the header before checking the stride of
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the increment against available space. Since C only allows incrementing
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pointers to one past the end of an array, the increment must be done
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after a length check. This commit fixes that and includes a regression
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test for CMSG_FIRSTHDR and CMSG_NXTHDR.
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The Linux, Hurd, and generic headers are all changed.
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Tested on Linux on armv7hl, i686, x86_64, aarch64, ppc64le, and s390x.
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[BZ #28846]
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Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
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Conflicts:
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socket/Makefile
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(usual test backport differences)
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diff --git a/bits/socket.h b/bits/socket.h
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index 725798882e4b803b..0474613a9c003eeb 100644
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--- a/bits/socket.h
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+++ b/bits/socket.h
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@@ -245,6 +245,12 @@ struct cmsghdr
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+ CMSG_ALIGN (sizeof (struct cmsghdr)))
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#define CMSG_LEN(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + (len))
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+/* Given a length, return the additional padding necessary such that
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+ len + __CMSG_PADDING(len) == CMSG_ALIGN (len). */
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+#define __CMSG_PADDING(len) ((sizeof (size_t) \
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+ - ((len) & (sizeof (size_t) - 1))) \
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+ & (sizeof (size_t) - 1))
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+
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extern struct cmsghdr *__cmsg_nxthdr (struct msghdr *__mhdr,
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struct cmsghdr *__cmsg) __THROW;
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#ifdef __USE_EXTERN_INLINES
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@@ -254,18 +260,38 @@ extern struct cmsghdr *__cmsg_nxthdr (struct msghdr *__mhdr,
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_EXTERN_INLINE struct cmsghdr *
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__NTH (__cmsg_nxthdr (struct msghdr *__mhdr, struct cmsghdr *__cmsg))
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{
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+ /* We may safely assume that __cmsg lies between __mhdr->msg_control and
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+ __mhdr->msg_controllen because the user is required to obtain the first
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+ cmsg via CMSG_FIRSTHDR, set its length, then obtain subsequent cmsgs
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+ via CMSG_NXTHDR, setting lengths along the way. However, we don't yet
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+ trust the value of __cmsg->cmsg_len and therefore do not use it in any
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+ pointer arithmetic until we check its value. */
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+
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+ unsigned char * __msg_control_ptr = (unsigned char *) __mhdr->msg_control;
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+ unsigned char * __cmsg_ptr = (unsigned char *) __cmsg;
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+
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+ size_t __size_needed = sizeof (struct cmsghdr)
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+ + __CMSG_PADDING (__cmsg->cmsg_len);
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+
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+ /* The current header is malformed, too small to be a full header. */
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if ((size_t) __cmsg->cmsg_len < sizeof (struct cmsghdr))
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- /* The kernel header does this so there may be a reason. */
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return (struct cmsghdr *) 0;
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+ /* There isn't enough space between __cmsg and the end of the buffer to
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+ hold the current cmsg *and* the next one. */
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+ if (((size_t)
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+ (__msg_control_ptr + __mhdr->msg_controllen - __cmsg_ptr)
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+ < __size_needed)
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+ || ((size_t)
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+ (__msg_control_ptr + __mhdr->msg_controllen - __cmsg_ptr
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+ - __size_needed)
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+ < __cmsg->cmsg_len))
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+
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+ return (struct cmsghdr *) 0;
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+
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+ /* Now, we trust cmsg_len and can use it to find the next header. */
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__cmsg = (struct cmsghdr *) ((unsigned char *) __cmsg
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+ CMSG_ALIGN (__cmsg->cmsg_len));
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- if ((unsigned char *) (__cmsg + 1) > ((unsigned char *) __mhdr->msg_control
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- + __mhdr->msg_controllen)
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- || ((unsigned char *) __cmsg + CMSG_ALIGN (__cmsg->cmsg_len)
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- > ((unsigned char *) __mhdr->msg_control + __mhdr->msg_controllen)))
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- /* No more entries. */
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- return (struct cmsghdr *) 0;
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return __cmsg;
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}
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#endif /* Use `extern inline'. */
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diff --git a/socket/Makefile b/socket/Makefile
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index 8975a65c2aabbfbc..a445383f8739351e 100644
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--- a/socket/Makefile
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+++ b/socket/Makefile
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@@ -31,7 +31,12 @@ routines := accept bind connect getpeername getsockname getsockopt \
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setsockopt shutdown socket socketpair isfdtype opensock \
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sockatmark accept4 recvmmsg sendmmsg sockaddr_un_set
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-tests := tst-accept4
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+tests := \
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+ tst-accept4 \
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+ tst-cmsghdr \
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+ # tests
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+
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+$(objpfx)tst-cmsghdr: $(libdl)
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tests-internal := \
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tst-sockaddr_un_set \
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diff --git a/socket/tst-cmsghdr-skeleton.c b/socket/tst-cmsghdr-skeleton.c
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new file mode 100644
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index 0000000000000000..7accfa6e54708e2a
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--- /dev/null
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+++ b/socket/tst-cmsghdr-skeleton.c
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@@ -0,0 +1,93 @@
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+/* Test ancillary data header creation.
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+ Copyright (C) 2022 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+/* We use the preprocessor to generate the function/macro tests instead of
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+ using indirection because having all the macro expansions alongside
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+ each other lets the compiler warn us about suspicious pointer
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+ arithmetic across subsequent CMSG_{FIRST,NXT}HDR expansions. */
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+
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+#include <stdint.h>
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+#include <stddef.h>
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+
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+#define RUN_TEST_CONCAT(suffix) run_test_##suffix
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+#define RUN_TEST_FUNCNAME(suffix) RUN_TEST_CONCAT (suffix)
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+
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+static void
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+RUN_TEST_FUNCNAME (CMSG_NXTHDR_IMPL) (void)
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+{
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+ struct msghdr m = {0};
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+ struct cmsghdr *cmsg;
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+ char cmsgbuf[3 * CMSG_SPACE (sizeof (PAYLOAD))] = {0};
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+
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+ m.msg_control = cmsgbuf;
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+ m.msg_controllen = sizeof (cmsgbuf);
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+
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+ /* First header should point to the start of the buffer. */
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+ cmsg = CMSG_FIRSTHDR (&m);
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+ TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
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+
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+ /* If the first header length consumes the entire buffer, there is no
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+ space remaining for additional headers. */
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+ cmsg->cmsg_len = sizeof (cmsgbuf);
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg == NULL);
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+
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+ /* The first header length is so big, using it would cause an overflow. */
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+ cmsg = CMSG_FIRSTHDR (&m);
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+ TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
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+ cmsg->cmsg_len = SIZE_MAX;
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg == NULL);
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+
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+ /* The first header leaves just enough space to hold another header. */
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+ cmsg = CMSG_FIRSTHDR (&m);
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+ TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
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+ cmsg->cmsg_len = sizeof (cmsgbuf) - sizeof (struct cmsghdr);
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg != NULL);
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+
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+ /* The first header leaves space but not enough for another header. */
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+ cmsg = CMSG_FIRSTHDR (&m);
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+ TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
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+ cmsg->cmsg_len ++;
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg == NULL);
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+
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+ /* The second header leaves just enough space to hold another header. */
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+ cmsg = CMSG_FIRSTHDR (&m);
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+ TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
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+ cmsg->cmsg_len = CMSG_LEN (sizeof (PAYLOAD));
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg != NULL);
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+ cmsg->cmsg_len = sizeof (cmsgbuf)
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+ - CMSG_SPACE (sizeof (PAYLOAD)) /* First header. */
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+ - sizeof (struct cmsghdr);
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg != NULL);
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+
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+ /* The second header leaves space but not enough for another header. */
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+ cmsg = CMSG_FIRSTHDR (&m);
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+ TEST_VERIFY_EXIT ((char *) cmsg == cmsgbuf);
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg != NULL);
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+ cmsg->cmsg_len ++;
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+ cmsg = CMSG_NXTHDR_IMPL (&m, cmsg);
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+ TEST_VERIFY_EXIT (cmsg == NULL);
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+
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+ return;
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+}
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diff --git a/socket/tst-cmsghdr.c b/socket/tst-cmsghdr.c
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new file mode 100644
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index 0000000000000000..68c96d3c9dd2bce8
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--- /dev/null
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+++ b/socket/tst-cmsghdr.c
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@@ -0,0 +1,56 @@
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+/* Test ancillary data header creation.
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+ Copyright (C) 2022 Free Software Foundation, Inc.
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+ This file is part of the GNU C Library.
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+
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+ The GNU C Library is free software; you can redistribute it and/or
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+ modify it under the terms of the GNU Lesser General Public
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+ License as published by the Free Software Foundation; either
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+ version 2.1 of the License, or (at your option) any later version.
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+
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+ The GNU C Library is distributed in the hope that it will be useful,
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+ but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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+ Lesser General Public License for more details.
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+
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+ You should have received a copy of the GNU Lesser General Public
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+ License along with the GNU C Library; if not, see
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+ <https://www.gnu.org/licenses/>. */
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+
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+#include <sys/socket.h>
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+#include <gnu/lib-names.h>
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+#include <support/xdlfcn.h>
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+#include <support/check.h>
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+
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+#define PAYLOAD "Hello, World!"
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+
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+/* CMSG_NXTHDR is a macro that calls an inline function defined in
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+ bits/socket.h. In case the function cannot be inlined, libc.so carries
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+ a copy. Both versions need to be tested. */
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+
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+#define CMSG_NXTHDR_IMPL CMSG_NXTHDR
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+#include "tst-cmsghdr-skeleton.c"
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+#undef CMSG_NXTHDR_IMPL
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+
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+static struct cmsghdr * (* cmsg_nxthdr) (struct msghdr *, struct cmsghdr *);
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+
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+#define CMSG_NXTHDR_IMPL cmsg_nxthdr
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+#include "tst-cmsghdr-skeleton.c"
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+#undef CMSG_NXTHDR_IMPL
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+
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+static int
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+do_test (void)
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+{
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+ static void *handle;
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+
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+ run_test_CMSG_NXTHDR ();
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+
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+ handle = xdlopen (LIBC_SO, RTLD_LAZY);
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+ cmsg_nxthdr = (struct cmsghdr * (*) (struct msghdr *, struct cmsghdr *))
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+ xdlsym (handle, "__cmsg_nxthdr");
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+
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+ run_test_cmsg_nxthdr ();
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+
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+ return 0;
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+}
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+
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+#include <support/test-driver.c>
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diff --git a/sysdeps/mach/hurd/bits/socket.h b/sysdeps/mach/hurd/bits/socket.h
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index 18959139dc7d325b..cc66684061e3e179 100644
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--- a/sysdeps/mach/hurd/bits/socket.h
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+++ b/sysdeps/mach/hurd/bits/socket.h
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@@ -249,6 +249,12 @@ struct cmsghdr
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+ CMSG_ALIGN (sizeof (struct cmsghdr)))
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#define CMSG_LEN(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + (len))
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+/* Given a length, return the additional padding necessary such that
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+ len + __CMSG_PADDING(len) == CMSG_ALIGN (len). */
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+#define __CMSG_PADDING(len) ((sizeof (size_t) \
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+ - ((len) & (sizeof (size_t) - 1))) \
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+ & (sizeof (size_t) - 1))
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+
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extern struct cmsghdr *__cmsg_nxthdr (struct msghdr *__mhdr,
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struct cmsghdr *__cmsg) __THROW;
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#ifdef __USE_EXTERN_INLINES
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@@ -258,18 +264,38 @@ extern struct cmsghdr *__cmsg_nxthdr (struct msghdr *__mhdr,
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_EXTERN_INLINE struct cmsghdr *
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__NTH (__cmsg_nxthdr (struct msghdr *__mhdr, struct cmsghdr *__cmsg))
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{
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+ /* We may safely assume that __cmsg lies between __mhdr->msg_control and
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+ __mhdr->msg_controllen because the user is required to obtain the first
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+ cmsg via CMSG_FIRSTHDR, set its length, then obtain subsequent cmsgs
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+ via CMSG_NXTHDR, setting lengths along the way. However, we don't yet
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+ trust the value of __cmsg->cmsg_len and therefore do not use it in any
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+ pointer arithmetic until we check its value. */
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+
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+ unsigned char * __msg_control_ptr = (unsigned char *) __mhdr->msg_control;
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+ unsigned char * __cmsg_ptr = (unsigned char *) __cmsg;
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+
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+ size_t __size_needed = sizeof (struct cmsghdr)
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+ + __CMSG_PADDING (__cmsg->cmsg_len);
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+
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+ /* The current header is malformed, too small to be a full header. */
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if ((size_t) __cmsg->cmsg_len < sizeof (struct cmsghdr))
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- /* The kernel header does this so there may be a reason. */
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return (struct cmsghdr *) 0;
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+ /* There isn't enough space between __cmsg and the end of the buffer to
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+ hold the current cmsg *and* the next one. */
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+ if (((size_t)
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+ (__msg_control_ptr + __mhdr->msg_controllen - __cmsg_ptr)
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+ < __size_needed)
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+ || ((size_t)
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+ (__msg_control_ptr + __mhdr->msg_controllen - __cmsg_ptr
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+ - __size_needed)
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+ < __cmsg->cmsg_len))
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+
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+ return (struct cmsghdr *) 0;
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+
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+ /* Now, we trust cmsg_len and can use it to find the next header. */
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__cmsg = (struct cmsghdr *) ((unsigned char *) __cmsg
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+ CMSG_ALIGN (__cmsg->cmsg_len));
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- if ((unsigned char *) (__cmsg + 1) > ((unsigned char *) __mhdr->msg_control
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- + __mhdr->msg_controllen)
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- || ((unsigned char *) __cmsg + CMSG_ALIGN (__cmsg->cmsg_len)
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- > ((unsigned char *) __mhdr->msg_control + __mhdr->msg_controllen)))
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- /* No more entries. */
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- return (struct cmsghdr *) 0;
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return __cmsg;
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}
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#endif /* Use `extern inline'. */
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diff --git a/sysdeps/unix/sysv/linux/bits/socket.h b/sysdeps/unix/sysv/linux/bits/socket.h
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index c3fbb2110296273c..6b895b89831d2cb5 100644
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--- a/sysdeps/unix/sysv/linux/bits/socket.h
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+++ b/sysdeps/unix/sysv/linux/bits/socket.h
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@@ -302,6 +302,12 @@ struct cmsghdr
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+ CMSG_ALIGN (sizeof (struct cmsghdr)))
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#define CMSG_LEN(len) (CMSG_ALIGN (sizeof (struct cmsghdr)) + (len))
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+/* Given a length, return the additional padding necessary such that
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+ len + __CMSG_PADDING(len) == CMSG_ALIGN (len). */
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+#define __CMSG_PADDING(len) ((sizeof (size_t) \
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+ - ((len) & (sizeof (size_t) - 1))) \
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+ & (sizeof (size_t) - 1))
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+
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extern struct cmsghdr *__cmsg_nxthdr (struct msghdr *__mhdr,
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struct cmsghdr *__cmsg) __THROW;
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#ifdef __USE_EXTERN_INLINES
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@@ -311,18 +317,38 @@ extern struct cmsghdr *__cmsg_nxthdr (struct msghdr *__mhdr,
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_EXTERN_INLINE struct cmsghdr *
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__NTH (__cmsg_nxthdr (struct msghdr *__mhdr, struct cmsghdr *__cmsg))
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{
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+ /* We may safely assume that __cmsg lies between __mhdr->msg_control and
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+ __mhdr->msg_controllen because the user is required to obtain the first
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+ cmsg via CMSG_FIRSTHDR, set its length, then obtain subsequent cmsgs
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+ via CMSG_NXTHDR, setting lengths along the way. However, we don't yet
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+ trust the value of __cmsg->cmsg_len and therefore do not use it in any
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+ pointer arithmetic until we check its value. */
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+
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+ unsigned char * __msg_control_ptr = (unsigned char *) __mhdr->msg_control;
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+ unsigned char * __cmsg_ptr = (unsigned char *) __cmsg;
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+
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+ size_t __size_needed = sizeof (struct cmsghdr)
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+ + __CMSG_PADDING (__cmsg->cmsg_len);
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+
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+ /* The current header is malformed, too small to be a full header. */
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if ((size_t) __cmsg->cmsg_len < sizeof (struct cmsghdr))
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- /* The kernel header does this so there may be a reason. */
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return (struct cmsghdr *) 0;
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+ /* There isn't enough space between __cmsg and the end of the buffer to
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+ hold the current cmsg *and* the next one. */
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+ if (((size_t)
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+ (__msg_control_ptr + __mhdr->msg_controllen - __cmsg_ptr)
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+ < __size_needed)
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+ || ((size_t)
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+ (__msg_control_ptr + __mhdr->msg_controllen - __cmsg_ptr
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+ - __size_needed)
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+ < __cmsg->cmsg_len))
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+
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+ return (struct cmsghdr *) 0;
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+
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+ /* Now, we trust cmsg_len and can use it to find the next header. */
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__cmsg = (struct cmsghdr *) ((unsigned char *) __cmsg
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+ CMSG_ALIGN (__cmsg->cmsg_len));
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- if ((unsigned char *) (__cmsg + 1) > ((unsigned char *) __mhdr->msg_control
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- + __mhdr->msg_controllen)
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- || ((unsigned char *) __cmsg + CMSG_ALIGN (__cmsg->cmsg_len)
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- > ((unsigned char *) __mhdr->msg_control + __mhdr->msg_controllen)))
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- /* No more entries. */
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- return (struct cmsghdr *) 0;
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return __cmsg;
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}
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#endif /* Use `extern inline'. */
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diff --git a/sysdeps/unix/sysv/linux/cmsg_nxthdr.c b/sysdeps/unix/sysv/linux/cmsg_nxthdr.c
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index bab0be6884d9da1c..16594622211c1c8b 100644
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--- a/sysdeps/unix/sysv/linux/cmsg_nxthdr.c
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+++ b/sysdeps/unix/sysv/linux/cmsg_nxthdr.c
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@@ -23,18 +23,38 @@
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struct cmsghdr *
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__cmsg_nxthdr (struct msghdr *mhdr, struct cmsghdr *cmsg)
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{
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+ /* We may safely assume that cmsg lies between mhdr->msg_control and
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+ mhdr->msg_controllen because the user is required to obtain the first
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+ cmsg via CMSG_FIRSTHDR, set its length, then obtain subsequent cmsgs
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+ via CMSG_NXTHDR, setting lengths along the way. However, we don't yet
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+ trust the value of cmsg->cmsg_len and therefore do not use it in any
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+ pointer arithmetic until we check its value. */
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+
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+ unsigned char * msg_control_ptr = (unsigned char *) mhdr->msg_control;
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+ unsigned char * cmsg_ptr = (unsigned char *) cmsg;
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+
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+ size_t size_needed = sizeof (struct cmsghdr)
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+ + __CMSG_PADDING (cmsg->cmsg_len);
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+
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+ /* The current header is malformed, too small to be a full header. */
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if ((size_t) cmsg->cmsg_len < sizeof (struct cmsghdr))
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- /* The kernel header does this so there may be a reason. */
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- return NULL;
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+ return (struct cmsghdr *) 0;
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+
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+ /* There isn't enough space between cmsg and the end of the buffer to
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+ hold the current cmsg *and* the next one. */
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+ if (((size_t)
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+ (msg_control_ptr + mhdr->msg_controllen - cmsg_ptr)
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+ < size_needed)
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+ || ((size_t)
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+ (msg_control_ptr + mhdr->msg_controllen - cmsg_ptr
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+ - size_needed)
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+ < cmsg->cmsg_len))
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+
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+ return (struct cmsghdr *) 0;
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+ /* Now, we trust cmsg_len and can use it to find the next header. */
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cmsg = (struct cmsghdr *) ((unsigned char *) cmsg
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+ CMSG_ALIGN (cmsg->cmsg_len));
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- if ((unsigned char *) (cmsg + 1) > ((unsigned char *) mhdr->msg_control
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- + mhdr->msg_controllen)
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- || ((unsigned char *) cmsg + CMSG_ALIGN (cmsg->cmsg_len)
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- > ((unsigned char *) mhdr->msg_control + mhdr->msg_controllen)))
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- /* No more entries. */
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- return NULL;
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return cmsg;
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}
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libc_hidden_def (__cmsg_nxthdr)
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