[PATCH AUTOSEL 5.4 097/330] btrfs: tree-checker: Check leaf chunk item size

Sasha Levin
2020-09-18T03:09:19Z

From: Qu Wenruo <wqu@suse.com>

[ Upstream commit f6d2a5c263afca84646cf3300dc13061bedbd99e ]

Inspired by btrfs-progs github issue #208, where chunk item in chunk
tree has invalid num_stripes (0).

Although that can already be caught by current btrfs_check_chunk_valid(),
that function doesn't really check item size as it needs to handle chunk
item in super block sys_chunk_array().

This patch will add two extra checks for chunk items in chunk tree:

- Basic chunk item size
If the item is smaller than btrfs_chunk (which already contains one
stripe), exit right now as reading num_stripes may even go beyond
eb boundary.

- Item size check against num_stripes
If item size doesn't match with calculated chunk size, then either the
item size or the num_stripes is corrupted. Error out anyway.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.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/tree-checker.c | 40 +++++++++++++++++++++++++++++++++++++++-
1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index 91ea38506fbb7..84b8d6ebf98f3 100644
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -674,6 +674,44 @@ int btrfs_check_chunk_valid(struct extent_buffer *leaf,
return 0;
}

+/*
+ * Enhanced version of chunk item checker.
+ *
+ * The common btrfs_check_chunk_valid() doesn't check item size since it needs
+ * to work on super block sys_chunk_array which doesn't have full item ptr.
+ */
+static int check_leaf_chunk_item(struct extent_buffer *leaf,
+ struct btrfs_chunk *chunk,
+ struct btrfs_key *key, int slot)
+{
+ int num_stripes;
+
+ if (btrfs_item_size_nr(leaf, slot) < sizeof(struct btrfs_chunk)) {
+ chunk_err(leaf, chunk, key->offset,
+ "invalid chunk item size: have %u expect [%zu, %u)",
+ btrfs_item_size_nr(leaf, slot),
+ sizeof(struct btrfs_chunk),
+ BTRFS_LEAF_DATA_SIZE(leaf->fs_info));
+ return -EUCLEAN;
+ }
+
+ num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
+ /* Let btrfs_check_chunk_valid() handle this error type */
+ if (num_stripes == 0)
+ goto out;
+
+ if (btrfs_chunk_item_size(num_stripes) !=
+ btrfs_item_size_nr(leaf, slot)) {
+ chunk_err(leaf, chunk, key->offset,
+ "invalid chunk item size: have %u expect %lu",
+ btrfs_item_size_nr(leaf, slot),
+ btrfs_chunk_item_size(num_stripes));
+ return -EUCLEAN;
+ }
+out:
+ return btrfs_check_chunk_valid(leaf, chunk, key->offset);
+}
+
__printf(3, 4)
__cold
static void dev_item_err(const struct extent_buffer *eb, int slot,
@@ -1265,7 +1303,7 @@ static int check_leaf_item(struct extent_buffer *leaf,
break;
case BTRFS_CHUNK_ITEM_KEY:
chunk = btrfs_item_ptr(leaf, slot, struct btrfs_chunk);
- ret = btrfs_check_chunk_valid(leaf, chunk, key->offset);
+ ret = check_leaf_chunk_item(leaf, chunk, key, slot);
break;
case BTRFS_DEV_ITEM_KEY:
ret = check_dev_item(leaf, key, slot);
--
2.25.1