When searching the extent tree to gather the needed extent info, btrfs_search_old_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_old_slot().
Found by code review.
Cc: stable@vger.kernel.org Fixes: 0b246afa62b0 ("btrfs: root->fs_info cleanup, add fs_info convenience variables") Signed-off-by: Ma Ke make24@iscas.ac.cn --- fs/btrfs/ctree.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 3dc5a35dd19b..4e2e1c38d33a 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2232,7 +2232,7 @@ ALLOW_ERROR_INJECTION(btrfs_search_slot, ERRNO); int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key, struct btrfs_path *p, u64 time_seq) { - struct btrfs_fs_info *fs_info = root->fs_info; + struct btrfs_fs_info *fs_info; struct extent_buffer *b; int slot; int ret; @@ -2241,6 +2241,10 @@ int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key, int lowest_unlock = 1; u8 lowest_level = 0;
+ if (!root) + return -EINVAL; + + fs_info = root->fs_info; lowest_level = p->lowest_level; WARN_ON(p->nodes[0] != NULL); ASSERT(!p->nowait);