Commit 3ed51857 authored by Lizhi Xu's avatar Lizhi Xu Committed by David Sterba
Browse files

btrfs: add a sanity check for btrfs root in btrfs_search_slot() 



Syzbot reports a null-ptr-deref in btrfs_search_slot().

The reproducer is using rescue=ibadroots, and the extent tree root is
corrupted thus the extent tree is NULL.

When scrub tries to search the extent tree to gather the needed extent
info, btrfs_search_slot() doesn't check if the target root is NULL or
not, resulting the null-ptr-deref.

Add sanity check for btrfs root before using it in btrfs_search_slot().

Reported-by: default avatar <syzbot+3030e17bd57a73d39bd7@syzkaller.appspotmail.com>
Fixes: 42437a63 ("btrfs: introduce mount option rescue=ignorebadroots")
Link: https://syzkaller.appspot.com/bug?extid=3030e17bd57a73d39bd7


CC: stable@vger.kernel.org # 5.15+
Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Tested-by: default avatar <syzbot+3030e17bd57a73d39bd7@syzkaller.appspotmail.com>
Signed-off-by: default avatarLizhi Xu <lizhi.xu@windriver.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent ed67f2a9

fs/btrfs/ctree.c

+5 −1
Original line number Diff line number Diff line
@@ -2046,7 +2046,7 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, 
		      const struct btrfs_key *key, struct btrfs_path *p,

		      int ins_len, int cow)

{

	struct btrfs_fs_info *fs_info = root->fs_info;

	struct btrfs_fs_info *fs_info;

	struct extent_buffer *b;

	int slot;

	int ret;
@@ -2059,6 +2059,10 @@ int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root *root, 
	int min_write_lock_level;

	int prev_cmp;



	if (!root)

		return -EINVAL;



	fs_info = root->fs_info;

	might_sleep();



	lowest_level = p->lowest_level;