From 34bb50c42335b9316cbdb9506c2c4126a66a52ee Mon Sep 17 00:00:00 2001 From: Julian Sun Date: Mon, 6 Jan 2025 10:34:31 +0800 Subject: [PATCH] ocfs2: check el->l_next_free_rec in ocfs2_get_clusters_nocache Recently syzbot reported a use-after-free issue[1]. The root cause of the problem is that the journal inode recorded in this file system image is corrupted. The value of "di->id2.i_list.l_next_free_rec" is 8193, which is greater than the value of "di->id2.i_list.l_count" (19). To solve this problem, an additional check should be added within ocfs2_get_clusters_nocache(). If the check fails, an error will be returned and the file system will be set to read-only. [1]: https://lore.kernel.org/all/67577778.050a0220.a30f1.01bc.GAE@google.com/T/ Link: https://lkml.kernel.org/r/20250106023432.1320904-1-sunjunchao2870@gmail.com Signed-off-by: Julian Sun Reported-by: syzbot+2313dda4dc4885c93578@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2313dda4dc4885c93578 Tested-by: syzbot+2313dda4dc4885c93578@syzkaller.appspotmail.com Reviewed-by: Joseph Qi Cc: Changwei Ge Cc: Joel Becker Cc: Jun Piao Cc: Junxiao Bi Cc: Mark Fasheh Signed-off-by: Andrew Morton --- fs/ocfs2/extent_map.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/ocfs2/extent_map.c b/fs/ocfs2/extent_map.c index f7672472fa82..930150ed5db1 100644 --- a/fs/ocfs2/extent_map.c +++ b/fs/ocfs2/extent_map.c @@ -435,6 +435,16 @@ static int ocfs2_get_clusters_nocache(struct inode *inode, } } + if (le16_to_cpu(el->l_next_free_rec) > le16_to_cpu(el->l_count)) { + ocfs2_error(inode->i_sb, + "Inode %lu has an invalid extent (next_free_rec %u, count %u)\n", + inode->i_ino, + le16_to_cpu(el->l_next_free_rec), + le16_to_cpu(el->l_count)); + ret = -EROFS; + goto out; + } + i = ocfs2_search_extent_list(el, v_cluster); if (i == -1) { /*