[PATCH AUTOSEL 5.4 10/17] btrfs: handle memory allocation failure in btrfs_csum_one_bio

[Sasha Levin <sashal@kernel.org>]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

[ Upstream commit 806570c0bb7b4847828c22c4934fcf2dc8fc572f ]

Since f8a53bb58ec7 ("btrfs: handle checksum generation in the storage
layer") the failures of btrfs_csum_one_bio() are handled via
bio_end_io().

This means, we can return BLK_STS_RESOURCE from btrfs_csum_one_bio() in
case the allocation of the ordered sums fails.

This also fixes a syzkaller report, where injecting a failure into the
kvzalloc() call results in a BUG_ON().

Reported-by: syzbot+d8941552e21eac774778@syzkaller.appspotmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.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/file-item.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 61b82c69eed50..1a7183cdfe950 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -499,7 +499,9 @@ blk_status_t btrfs_csum_one_bio(struct inode *inode, struct bio *bio,
 				sums = kvzalloc(btrfs_ordered_sum_size(fs_info,
 						      bytes_left), GFP_KERNEL);
 				memalloc_nofs_restore(nofs_flag);
-				BUG_ON(!sums); /* -ENOMEM */
+				if (!sums)
+					return BLK_STS_RESOURCE;
+
 				sums->len = bytes_left;
 				ordered = btrfs_lookup_ordered_extent(inode,
 								offset);
-- 
2.39.2