From 315bed43fea532650933e7bba316a7601d439edf Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Thu, 13 Sep 2018 11:35:10 +0300 Subject: [PATCH] btrfs: handle error of get_old_root In btrfs_search_old_slot get_old_root is always used with the assumption it cannot fail. However, this is not true in rare circumstance it can fail and return null. This will lead to null point dereference when the header is read. Fix this by checking the return value and properly handling NULL by setting ret to -EIO and returning gracefully. Coverity-id: 1087503 Signed-off-by: Nikolay Borisov Reviewed-by: Lu Fengqi Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/ctree.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 6178fadf80a1..0a6c645fab0a 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2960,6 +2960,10 @@ int btrfs_search_old_slot(struct btrfs_root *root, const struct btrfs_key *key, again: b = get_old_root(root, time_seq); + if (!b) { + ret = -EIO; + goto done; + } level = btrfs_header_level(b); p->locks[level] = BTRFS_READ_LOCK;