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glibc/glibc-RHEL-56542-7.patch
Frédéric Bérat d2c49567f7 Backport test implementation to verify readdir behavior 
Resolves: RHEL-56542
2025-01-10 11:22:50 +01:00

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commit e92718552e1d17b8eccbffb88bf5bbb2235c4596
Author: Florian Weimer <fweimer@redhat.com>
Date: Sat Sep 21 19:32:34 2024 +0200
Linux: Use readdir64_r for compat __old_readdir64_r (bug 32128)
It is not necessary to do the conversion at the getdents64
layer for readdir64_r. Doing it piecewise for readdir64
is slightly simpler and allows deleting __old_getdents64.
This fixes bug 32128 because readdir64_r handles the length
check correctly.
Reviewed-by: DJ Delorie <dj@redhat.com>
diff --git a/sysdeps/unix/sysv/linux/getdents64.c b/sysdeps/unix/sysv/linux/getdents64.c
index 6323e003b30ae0e6..6f8e9147fbfb79bc 100644
--- a/sysdeps/unix/sysv/linux/getdents64.c
+++ b/sysdeps/unix/sysv/linux/getdents64.c
@@ -33,100 +33,3 @@ __getdents64 (int fd, void *buf, size_t nbytes)
}
libc_hidden_def (__getdents64)
weak_alias (__getdents64, getdents64)
-
-#if _DIRENT_MATCHES_DIRENT64
-strong_alias (__getdents64, __getdents)
-#else
-# include <shlib-compat.h>
-
-# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
-# include <olddirent.h>
-# include <unistd.h>
-
-static ssize_t
-handle_overflow (int fd, __off64_t offset, ssize_t count)
-{
- /* If this is the first entry in the buffer, we can report the
- error. */
- if (offset == 0)
- {
- __set_errno (EOVERFLOW);
- return -1;
- }
-
- /* Otherwise, seek to the overflowing entry, so that the next call
- will report the error, and return the data read so far. */
- if (__lseek64 (fd, offset, SEEK_SET) != 0)
- return -1;
- return count;
-}
-
-ssize_t
-__old_getdents64 (int fd, char *buf, size_t nbytes)
-{
- /* We do not move the individual directory entries. This is only
- possible if the target type (struct __old_dirent64) is smaller
- than the source type. */
- _Static_assert (offsetof (struct __old_dirent64, d_name)
- <= offsetof (struct dirent64, d_name),
- "__old_dirent64 is larger than dirent64");
- _Static_assert (__alignof__ (struct __old_dirent64)
- <= __alignof__ (struct dirent64),
- "alignment of __old_dirent64 is larger than dirent64");
-
- ssize_t retval = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
- if (retval > 0)
- {
- /* This is the marker for the first entry. Offset 0 is reserved
- for the first entry (see rewinddir). Here, we use it as a
- marker for the first entry in the buffer. We never actually
- seek to offset 0 because handle_overflow reports the error
- directly, so it does not matter that the offset is incorrect
- if entries have been read from the descriptor before (so that
- the descriptor is not actually at offset 0). */
- __off64_t previous_offset = 0;
-
- char *p = buf;
- char *end = buf + retval;
- while (p < end)
- {
- struct dirent64 *source = (struct dirent64 *) p;
-
- /* Copy out the fixed-size data. */
- __ino_t ino = source->d_ino;
- __off64_t offset = source->d_off;
- unsigned int reclen = source->d_reclen;
- unsigned char type = source->d_type;
-
- /* Check for ino_t overflow. */
- if (__glibc_unlikely (ino != source->d_ino))
- return handle_overflow (fd, previous_offset, p - buf);
-
- /* Convert to the target layout. Use a separate struct and
- memcpy to side-step aliasing issues. */
- struct __old_dirent64 result;
- result.d_ino = ino;
- result.d_off = offset;
- result.d_reclen = reclen;
- result.d_type = type;
-
- /* Write the fixed-sized part of the result to the
- buffer. */
- size_t result_name_offset = offsetof (struct __old_dirent64, d_name);
- memcpy (p, &result, result_name_offset);
-
- /* Adjust the position of the name if necessary. Copy
- everything until the end of the record, including the
- terminating NUL byte. */
- if (result_name_offset != offsetof (struct dirent64, d_name))
- memmove (p + result_name_offset, source->d_name,
- reclen - offsetof (struct dirent64, d_name));
-
- p += reclen;
- previous_offset = offset;
- }
- }
- return retval;
-}
-# endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2) */
-#endif /* _DIRENT_MATCHES_DIRENT64 */
diff --git a/sysdeps/unix/sysv/linux/olddirent.h b/sysdeps/unix/sysv/linux/olddirent.h
index 3e672d47f5a5e421..d1a486e855e744c3 100644
--- a/sysdeps/unix/sysv/linux/olddirent.h
+++ b/sysdeps/unix/sysv/linux/olddirent.h
@@ -34,8 +34,6 @@ extern struct __old_dirent64 *__old_readdir64 (DIR *__dirp);
libc_hidden_proto (__old_readdir64);
extern int __old_readdir64_r (DIR *__dirp, struct __old_dirent64 *__entry,
struct __old_dirent64 **__result);
-extern __ssize_t __old_getdents64 (int __fd, char *__buf, size_t __nbytes)
- attribute_hidden;
int __old_scandir64 (const char * __dir,
struct __old_dirent64 *** __namelist,
int (*__selector) (const struct __old_dirent64 *),
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index 8a60504649aa54a2..c3450b083b6b64cf 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -26,17 +26,13 @@
#undef __readdir
#undef readdir
-/* Read a directory entry from DIRP. */
-struct dirent64 *
-__readdir64 (DIR *dirp)
+/* Read a directory entry from DIRP. No locking. */
+static struct dirent64 *
+__readdir64_unlocked (DIR *dirp)
{
struct dirent64 *dp;
int saved_errno = errno;
-#if IS_IN (libc)
- __libc_lock_lock (dirp->lock);
-#endif
-
if (dirp->offset >= dirp->size)
{
/* We've emptied out our buffer. Refill it. */
@@ -53,9 +49,6 @@ __readdir64 (DIR *dirp)
do not set errno in that case, to indicate success. */
if (bytes == 0 || errno == ENOENT)
__set_errno (saved_errno);
-#if IS_IN (libc)
- __libc_lock_unlock (dirp->lock);
-#endif
return NULL;
}
dirp->size = (size_t) bytes;
@@ -68,10 +61,16 @@ __readdir64 (DIR *dirp)
dirp->offset += dp->d_reclen;
dirp->filepos = dp->d_off;
-#if IS_IN (libc)
- __libc_lock_unlock (dirp->lock);
-#endif
+ return dp;
+}
+/* Read a directory entry from DIRP. */
+struct dirent64 *
+__readdir64 (DIR *dirp)
+{
+ __libc_lock_lock (dirp->lock);
+ struct dirent64 *dp = __readdir64_unlocked (dirp);
+ __libc_lock_unlock (dirp->lock);
return dp;
}
libc_hidden_def (__readdir64)
@@ -99,45 +98,54 @@ __old_readdir64 (DIR *dirp)
struct __old_dirent64 *dp;
int saved_errno = errno;
-#if IS_IN (libc)
__libc_lock_lock (dirp->lock);
-#endif
- if (dirp->offset >= dirp->size)
+ while (1)
{
- /* We've emptied out our buffer. Refill it. */
+ errno = 0;
+ struct dirent64 *newdp = __readdir64_unlocked (dirp);
+ if (newdp == NULL)
+ {
+ if (errno == 0 && dirp->errcode != 0)
+ __set_errno (dirp->errcode);
+ else if (errno == 0)
+ __set_errno (saved_errno);
+ dp = NULL;
+ break;
+ }
- size_t maxread = dirp->allocation;
- ssize_t bytes;
+ /* Convert to the target layout. Use a separate struct and
+ memcpy to side-step aliasing issues. */
+ struct __old_dirent64 result;
+ result.d_ino = newdp->d_ino;
+ result.d_off = newdp->d_off;
+ result.d_reclen = newdp->d_reclen;
+ result.d_type = newdp->d_type;
- bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
- if (bytes <= 0)
+ /* Check for ino_t overflow. */
+ if (__glibc_unlikely (result.d_ino != newdp->d_ino))
{
- /* Linux may fail with ENOENT on some file systems if the
- directory inode is marked as dead (deleted). POSIX
- treats this as a regular end-of-directory condition, so
- do not set errno in that case, to indicate success. */
- if (bytes == 0 || errno == ENOENT)
- __set_errno (saved_errno);
-#if IS_IN (libc)
- __libc_lock_unlock (dirp->lock);
-#endif
- return NULL;
+ dirp->errcode = ENAMETOOLONG;
+ continue;
}
- dirp->size = (size_t) bytes;
- /* Reset the offset into the buffer. */
- dirp->offset = 0;
- }
+ /* Overwrite the fixed-sized part. */
+ dp = (struct __old_dirent64 *) newdp;
+ memcpy (dp, &result, offsetof (struct __old_dirent64, d_name));
- dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
- dirp->offset += dp->d_reclen;
- dirp->filepos = dp->d_off;
+ /* Move the name. */
+ _Static_assert (offsetof (struct __old_dirent64, d_name)
+ <= offsetof (struct dirent64, d_name),
+ "old struct must be smaller");
+ if (offsetof (struct __old_dirent64, d_name)
+ != offsetof (struct dirent64, d_name))
+ memmove (dp->d_name, newdp->d_name, strlen (newdp->d_name) + 1);
-#if IS_IN (libc)
- __libc_lock_unlock (dirp->lock);
-#endif
+ __set_errno (saved_errno);
+ break;
+ }
+ __libc_lock_unlock (dirp->lock);
return dp;
}
libc_hidden_def (__old_readdir64)
diff --git a/sysdeps/unix/sysv/linux/readdir64_r.c b/sysdeps/unix/sysv/linux/readdir64_r.c
index 073a6453d1bbbd61..0c60987343b1f37f 100644
--- a/sysdeps/unix/sysv/linux/readdir64_r.c
+++ b/sysdeps/unix/sysv/linux/readdir64_r.c
@@ -135,91 +135,37 @@ attribute_compat_text_section
__old_readdir64_r (DIR *dirp, struct __old_dirent64 *entry,
struct __old_dirent64 **result)
{
- struct __old_dirent64 *dp;
- size_t reclen;
- const int saved_errno = errno;
- int ret;
-
- __libc_lock_lock (dirp->lock);
-
- do
+ while (1)
{
- if (dirp->offset >= dirp->size)
- {
- /* We've emptied out our buffer. Refill it. */
-
- size_t maxread = dirp->allocation;
- ssize_t bytes;
-
- maxread = dirp->allocation;
-
- bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
- if (bytes <= 0)
- {
- /* On some systems getdents fails with ENOENT when the
- open directory has been rmdir'd already. POSIX.1
- requires that we treat this condition like normal EOF. */
- if (bytes < 0 && errno == ENOENT)
- {
- bytes = 0;
- __set_errno (saved_errno);
- }
- if (bytes < 0)
- dirp->errcode = errno;
+ struct dirent64 new_entry;
+ struct dirent64 *newp;
+ int ret = __readdir64_r (dirp, &new_entry, &newp);
- dp = NULL;
- break;
- }
- dirp->size = (size_t) bytes;
-
- /* Reset the offset into the buffer. */
- dirp->offset = 0;
+ if (ret != 0)
+ return ret;
+ else if (newp == NULL)
+ {
+ *result = NULL;
+ return 0;
}
-
- dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
-
- reclen = dp->d_reclen;
-
- dirp->offset += reclen;
-
- dirp->filepos = dp->d_off;
-
- if (reclen > offsetof (struct __old_dirent64, d_name) + NAME_MAX + 1)
+ else
{
- /* The record is very long. It could still fit into the
- caller-supplied buffer if we can skip padding at the
- end. */
- size_t namelen = _D_EXACT_NAMLEN (dp);
- if (namelen <= NAME_MAX)
- reclen = offsetof (struct __old_dirent64, d_name) + namelen + 1;
- else
+ entry->d_ino = newp->d_ino;
+ if (entry->d_ino != newp->d_ino)
{
- /* The name is too long. Ignore this file. */
- dirp->errcode = ENAMETOOLONG;
- dp->d_ino = 0;
+ dirp->errcode = EOVERFLOW;
continue;
}
+ size_t namelen = strlen (newp->d_name);
+ entry->d_off = newp->d_off;
+ entry->d_reclen = (offsetof (struct __old_dirent64, d_name)
+ + namelen + 1);
+ entry->d_type = newp->d_type;
+ memcpy (entry->d_name, newp->d_name, namelen + 1);
+ *result = entry;
+ return 0;
}
-
- /* Skip deleted and ignored files. */
- }
- while (dp->d_ino == 0);
-
- if (dp != NULL)
- {
- *result = memcpy (entry, dp, reclen);
- entry->d_reclen = reclen;
- ret = 0;
}
- else
- {
- *result = NULL;
- ret = dirp->errcode;
- }
-
- __libc_lock_unlock (dirp->lock);
-
- return ret;
}
compat_symbol (libc, __old_readdir64_r, readdir64_r, GLIBC_2_1);
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