From 390ac56cf0f687de53695648bc6f2259a7eae429 Mon Sep 17 00:00:00 2001 From: Dmitry Antipov Date: Mon, 13 Oct 2025 09:28:26 +0300 Subject: [PATCH] ocfs2: add boundary check to ocfs2_check_dir_entry() 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 Reported-by: syzbot+b20bbf680bb0f2ecedae@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b20bbf680bb0f2ecedae Reviewed-by: Heming Zhao Cc: Joseph Qi Cc: Mark Fasheh Cc: Joel Becker Cc: Junxiao Bi Cc: Changwei Ge Cc: Jun Piao Signed-off-by: Andrew Morton --- fs/ocfs2/dir.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/fs/ocfs2/dir.c b/fs/ocfs2/dir.c index dc3d66263335d..2785ff245e79e 100644 --- a/fs/ocfs2/dir.c +++ b/fs/ocfs2/dir.c @@ -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"; -- 2.47.3