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ocfs2: add boundary check to ocfs2_check_dir_entry()

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In 'ocfs2_check_dir_entry()', add extra check whether at least the
smallest possible dirent may be located at the specified offset within
bh's data, thus preventing an out-of-bounds accesses below.

Link: https://lkml.kernel.org/r/20251013062826.122586-1-dmantipov@yandex.ru
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Reported-by: syzbot+b20bbf680bb0f2ecedae@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b20bbf680bb0f2ecedae
Reviewed-by: Heming Zhao <heming.zhao@suse.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Dmitry Antipov
2025-10-13 09:28:26 +03:00
committed by Andrew Morton
parent d99dc586ca
commit 390ac56cf0
1 changed files with 15 additions and 2 deletions
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17
fs/ocfs2/dir.c
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@@ -302,8 +302,21 @@ static int ocfs2_check_dir_entry(struct inode *dir,
unsigned long offset)
{
const char *error_msg = NULL;
const int rlen = le16_to_cpu(de->rec_len);
const unsigned long next_offset = ((char *) de - buf) + rlen;
unsigned long next_offset;
int rlen;
if (offset > size - OCFS2_DIR_REC_LEN(1)) {
/* Dirent is (maybe partially) beyond the buffer
* boundaries so touching 'de' members is unsafe.
*/
mlog(ML_ERROR, "directory entry (#%llu: offset=%lu) "
"too close to end or out-of-bounds",
(unsigned long long)OCFS2_I(dir)->ip_blkno, offset);
return 0;
}
rlen = le16_to_cpu(de->rec_len);
next_offset = ((char *) de - buf) + rlen;
if (unlikely(rlen < OCFS2_DIR_REC_LEN(1)))
error_msg = "rec_len is smaller than minimal";