[PATCH 4.19 102/190] btrfs: init csum_list before possible free

Greg Kroah-Hartman
2019-09-13T13:30:55Z

[ Upstream commit e49be14b8d80e23bb7c53d78c21717a474ade76b ]

The scrub_ctx csum_list member must be initialized before scrub_free_ctx
is called. If the csum_list is not initialized beforehand, the
list_empty call in scrub_free_csums will result in a null deref if the
allocation fails in the for loop.

Fixes: a2de733c78fa ("btrfs: scrub")
CC: stable@vger.kernel.org # 3.0+
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/scrub.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
index a08a4d6f540f9..916c397704679 100644
--- a/fs/btrfs/scrub.c
+++ b/fs/btrfs/scrub.c
@@ -592,6 +592,7 @@ static noinline_for_stack struct scrub_ctx *scrub_setup_ctx(
sctx->pages_per_rd_bio = SCRUB_PAGES_PER_RD_BIO;
sctx->curr = -1;
sctx->fs_info = fs_info;
+ INIT_LIST_HEAD(&sctx->csum_list);
for (i = 0; i < SCRUB_BIOS_PER_SCTX; ++i) {
struct scrub_bio *sbio;

@@ -616,7 +617,6 @@ static noinline_for_stack struct scrub_ctx *scrub_setup_ctx(
atomic_set(&sctx->workers_pending, 0);
atomic_set(&sctx->cancel_req, 0);
sctx->csum_size = btrfs_super_csum_size(fs_info->super_copy);
- INIT_LIST_HEAD(&sctx->csum_list);

spin_lock_init(&sctx->list_lock);
spin_lock_init(&sctx->stat_lock);
--
2.20.1