From: Deepanshu Kartikey Date: Tue, 31 Mar 2026 17:52:09 +0000 (+0900) Subject: nilfs2: reject zero bd_oblocknr in nilfs_ioctl_mark_blocks_dirty() X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=be3e5d10643d3be1cbac9d9939f220a99253f980;p=thirdparty%2Flinux.git nilfs2: reject zero bd_oblocknr in nilfs_ioctl_mark_blocks_dirty() nilfs_ioctl_mark_blocks_dirty() uses bd_oblocknr to detect dead blocks by comparing it with the current block number bd_blocknr. If they differ, the block is considered dead and skipped. However, bd_oblocknr should never be 0 since block 0 typically stores the primary superblock and is never a valid GC target block. A corrupted ioctl request with bd_oblocknr set to 0 causes the comparison to incorrectly match when the lookup returns -ENOENT and sets bd_blocknr to 0, bypassing the dead block check and calling nilfs_bmap_mark() on a non-existent block. This causes nilfs_btree_do_lookup() to return -ENOENT, triggering the WARN_ON(ret == -ENOENT). Fix this by rejecting ioctl requests with bd_oblocknr set to 0 at the beginning of each iteration. [ryusuke: slightly modified the commit message and comments for accuracy] Fixes: 7942b919f732 ("nilfs2: ioctl operations") Reported-by: syzbot+98a040252119df0506f8@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=98a040252119df0506f8 Suggested-by: Ryusuke Konishi Signed-off-by: Deepanshu Kartikey Reported-by: syzbot+466a45fcfb0562f5b9a0@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=466a45fcfb0562f5b9a0 Cc: Junjie Cao Signed-off-by: Ryusuke Konishi Signed-off-by: Viacheslav Dubeyko --- diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c index e17b8da664913..e0a606643e879 100644 --- a/fs/nilfs2/ioctl.c +++ b/fs/nilfs2/ioctl.c @@ -736,6 +736,12 @@ static int nilfs_ioctl_mark_blocks_dirty(struct the_nilfs *nilfs, int ret, i; for (i = 0; i < nmembs; i++) { + /* + * bd_oblocknr must never be 0 as block 0 + * is never a valid GC target block + */ + if (unlikely(!bdescs[i].bd_oblocknr)) + return -EINVAL; /* XXX: use macro or inline func to check liveness */ ret = nilfs_bmap_lookup_at_level(bmap, bdescs[i].bd_offset,