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Correct locking and cancellation cleanup in syslog functions (RHEL-78390)

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Resolves: RHEL-78390
This commit is contained in:
Patsy Griffin 2025-02-13 15:43:51 -05:00
parent 05fdc91196
commit c78c7515ed
2 changed files with 119 additions and 1 deletions
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114
glibc-RHEL-78390.patch Normal file
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@ -0,0 +1,114 @@
commit c4e4b2e149705559d28b16a9b47ba2f6142d6a6c
Author: Andreas Schwab <schwab@suse.de>
Date: Tue Jun 23 12:55:49 2020 +0200
Correct locking and cancellation cleanup in syslog functions (bug 26100)
Properly serialize the access to the global state shared between the
syslog functions, to avoid races in multithreaded processes. Protect a
local allocation in the __vsyslog_internal function from leaking during
cancellation.
diff --git a/misc/syslog.c b/misc/syslog.c
index fd6537edf6..2cc63ef287 100644
--- a/misc/syslog.c
+++ b/misc/syslog.c
@@ -91,14 +91,20 @@ struct cleanup_arg
static void
cancel_handler (void *ptr)
{
-#ifndef NO_SIGPIPE
/* Restore the old signal handler. */
struct cleanup_arg *clarg = (struct cleanup_arg *) ptr;
- if (clarg != NULL && clarg->oldaction != NULL)
- __sigaction (SIGPIPE, clarg->oldaction, NULL);
+ if (clarg != NULL)
+ {
+#ifndef NO_SIGPIPE
+ if (clarg->oldaction != NULL)
+ __sigaction (SIGPIPE, clarg->oldaction, NULL);
#endif
+ /* Free the memstream buffer, */
+ free (clarg->buf);
+ }
+
/* Free the lock. */
__libc_lock_unlock (syslog_lock);
}
@@ -169,9 +175,17 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
pri &= LOG_PRIMASK|LOG_FACMASK;
}
+ /* Prepare for multiple users. We have to take care: most
+ syscalls we are using are cancellation points. */
+ struct cleanup_arg clarg;
+ clarg.buf = NULL;
+ clarg.oldaction = NULL;
+ __libc_cleanup_push (cancel_handler, &clarg);
+ __libc_lock_lock (syslog_lock);
+
/* Check priority against setlogmask values. */
if ((LOG_MASK (LOG_PRI (pri)) & LogMask) == 0)
- return;
+ goto out;
/* Set default facility if none specified. */
if ((pri & LOG_FACMASK) == 0)
@@ -235,6 +249,9 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
/* Close the memory stream; this will finalize the data
into a malloc'd buffer in BUF. */
fclose (f);
+
+ /* Tell the cancellation handler to free this buffer. */
+ clarg.buf = buf;
}
/* Output to stderr if requested. */
@@ -252,22 +269,10 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
v->iov_len = 1;
}
- __libc_cleanup_push (free, buf == failbuf ? NULL : buf);
-
/* writev is a cancellation point. */
(void)__writev(STDERR_FILENO, iov, v - iov + 1);
-
- __libc_cleanup_pop (0);
}
- /* Prepare for multiple users. We have to take care: open and
- write are cancellation points. */
- struct cleanup_arg clarg;
- clarg.buf = buf;
- clarg.oldaction = NULL;
- __libc_cleanup_push (cancel_handler, &clarg);
- __libc_lock_lock (syslog_lock);
-
#ifndef NO_SIGPIPE
/* Prepare for a broken connection. */
memset (&action, 0, sizeof (action));
@@ -320,6 +325,7 @@ __vsyslog_internal(int pri, const char *fmt, va_list ap,
__sigaction (SIGPIPE, &oldaction, (struct sigaction *) NULL);
#endif
+ out:
/* End of critical section. */
__libc_cleanup_pop (0);
__libc_lock_unlock (syslog_lock);
@@ -430,8 +436,14 @@ setlogmask (int pmask)
{
int omask;
+ /* Protect against multiple users. */
+ __libc_lock_lock (syslog_lock);
+
omask = LogMask;
if (pmask != 0)
LogMask = pmask;
+
+ __libc_lock_unlock (syslog_lock);
+
return (omask);
}

6
glibc.spec
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@ -115,7 +115,7 @@ end \
Summary: The GNU libc libraries
Name: glibc
Version: %{glibcversion}
Release: %{glibcrelease}.13
Release: %{glibcrelease}.14
# In general, GPLv2+ is used by programs, LGPLv2+ is used for
# libraries.
@ -1258,6 +1258,7 @@ Patch1023: glibc-RHEL-8381-7.patch
Patch1024: glibc-RHEL-8381-8.patch
Patch1025: glibc-RHEL-8381-9.patch
Patch1026: glibc-RHEL-8381-10.patch
Patch1027: glibc-RHEL-78390.patch
##############################################################################
# Continued list of core "glibc" package information:
@ -2919,6 +2920,9 @@ fi
%{_libdir}/libpthread_nonshared.a
%changelog
* Tue Feb 11 2025 Patsy Griffin <patsy@redhat.com> - 2.28-251.14
- Correct locking and cancellation cleanup in syslog functions (RHEL-78390)
* Fri Feb 7 2025 Carlos O'Donell <carlos@redhat.com> - 2.28-251.13
- Restore internal ABI to avoid tooling false positives (RHEL-8381)