[PATCH 3.16 022/245] btrfs: add more checks to btrfs_read_sys_array

Ben Hutchings
2020-04-23T23:25:05Z

From: David Sterba <dsterba@suse.cz>

commit e3540eab29e1b2260bc4b9b3979a49a00e3e3af8 upstream.

Verify that the sys_array has enough bytes to read the next item.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/volumes.c | 26 +++++++++++++++++++++++---
1 file changed, 23 insertions(+), 3 deletions(-)

--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6071,20 +6071,34 @@ int btrfs_read_sys_array(struct btrfs_ro

while (cur_offset < array_size) {
disk_key = (struct btrfs_disk_key *)array_ptr;
+ len = sizeof(*disk_key);
+ if (cur_offset + len > array_size)
+ goto out_short_read;
+
btrfs_disk_key_to_cpu(&key, disk_key);

- len = sizeof(*disk_key);
array_ptr += len;
sb_array_offset += len;
cur_offset += len;

if (key.type == BTRFS_CHUNK_ITEM_KEY) {
chunk = (struct btrfs_chunk *)sb_array_offset;
+ /*
+ * At least one btrfs_chunk with one stripe must be
+ * present, exact stripe count check comes afterwards
+ */
+ len = btrfs_chunk_item_size(1);
+ if (cur_offset + len > array_size)
+ goto out_short_read;
+
+ num_stripes = btrfs_chunk_num_stripes(sb, chunk);
+ len = btrfs_chunk_item_size(num_stripes);
+ if (cur_offset + len > array_size)
+ goto out_short_read;
+
ret = read_one_chunk(root, &key, sb, chunk);
if (ret)
break;
- num_stripes = btrfs_chunk_num_stripes(sb, chunk);
- len = btrfs_chunk_item_size(num_stripes);
} else {
ret = -EIO;
break;
@@ -6095,6 +6109,12 @@ int btrfs_read_sys_array(struct btrfs_ro
}
free_extent_buffer(sb);
return ret;
+
+out_short_read:
+ printk(KERN_ERR "BTRFS: sys_array too short to read %u bytes at offset %u\n",
+ len, cur_offset);
+ free_extent_buffer(sb);
+ return -EIO;
}

int btrfs_read_chunk_tree(struct btrfs_root *root)