From 40d40c6bea19ff1e40fb3d33b35b354a5b35025f Mon Sep 17 00:00:00 2001 From: Diogo Jahchan Koike Date: Mon, 23 Sep 2024 19:22:14 -0300 Subject: bcachefs: assign return error when iterating through layout syzbot reported a null ptr deref in __copy_user [0] In __bch2_read_super, when a corrupt backup superblock matches the default opts offset, no error is assigned to ret and the freed superblock gets through, possibly being assigned as the best sb in bch2_fs_open and being later dereferenced, causing a fault. Assign EINVALID to ret when iterating through layout. [0]: https://syzkaller.appspot.com/bug?extid=18a5c5e8a9c856944876 Reported-by: syzbot+18a5c5e8a9c856944876@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=18a5c5e8a9c856944876 Signed-off-by: Diogo Jahchan Koike Signed-off-by: Kent Overstreet --- fs/bcachefs/super-io.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/bcachefs/super-io.c b/fs/bcachefs/super-io.c index d86d5dae54c9..b2e914841b5f 100644 --- a/fs/bcachefs/super-io.c +++ b/fs/bcachefs/super-io.c @@ -799,8 +799,10 @@ retry: i < layout.sb_offset + layout.nr_superblocks; i++) { offset = le64_to_cpu(*i); - if (offset == opt_get(*opts, sb)) + if (offset == opt_get(*opts, sb)) { + ret = -BCH_ERR_invalid; continue; + } ret = read_one_super(sb, offset, &err); if (!ret) -- cgit v1.2.3