[PATCH 5.4 264/344] btrfs: fix possible NULL-pointer dereference in integrity checks

Greg Kroah-Hartman
2020-02-21T08:14:02Z

From: Johannes Thumshirn <jth@kernel.org>

[ Upstream commit 3dbd351df42109902fbcebf27104149226a4fcd9 ]

A user reports a possible NULL-pointer dereference in
btrfsic_process_superblock(). We are assigning state->fs_info to a local
fs_info variable and afterwards checking for the presence of state.

While we would BUG_ON() a NULL state anyways, we can also just remove
the local fs_info copy, as fs_info is only used once as the first
argument for btrfs_num_copies(). There we can just pass in
state->fs_info as well.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=205003
Signed-off-by: Johannes Thumshirn <jth@kernel.org>
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/check-integrity.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/btrfs/check-integrity.c b/fs/btrfs/check-integrity.c
index 0b52ab4cb9649..72c70f59fc605 100644
--- a/fs/btrfs/check-integrity.c
+++ b/fs/btrfs/check-integrity.c
@@ -629,7 +629,6 @@ static struct btrfsic_dev_state *btrfsic_dev_state_hashtable_lookup(dev_t dev,
static int btrfsic_process_superblock(struct btrfsic_state *state,
struct btrfs_fs_devices *fs_devices)
{
- struct btrfs_fs_info *fs_info = state->fs_info;
struct btrfs_super_block *selected_super;
struct list_head *dev_head = &fs_devices->devices;
struct btrfs_device *device;
@@ -700,7 +699,7 @@ static int btrfsic_process_superblock(struct btrfsic_state *state,
break;
}

- num_copies = btrfs_num_copies(fs_info, next_bytenr,
+ num_copies = btrfs_num_copies(state->fs_info, next_bytenr,
state->metablock_size);
if (state->print_mask & BTRFSIC_PRINT_MASK_NUM_COPIES)
pr_info("num_copies(log_bytenr=%llu) = %d\n",
--
2.20.1