btrfs: handle memory allocation failure in btrfs_csum_one_bio

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>

diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index cd4cce9..d1cd0a6 100644 (file)
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -792,7 +792,9 @@ blk_status_t btrfs_csum_one_bio(struct btrfs_bio *bbio)
                                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);