btrfs: tree-checker: validate number of chunk stripes and parity

If there's no parity and num_stripes < ncopies, a crafted image can
trigger a division by zero in calc_stripe_length().

The image was generated through fuzzing.

CC: stable@vger.kernel.org # 5.4+
Reviewed-by: Qu Wenruo <wqu@suse.com>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=209587
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c
index f0ffd5e..8784b74 100644 (file)
--- a/fs/btrfs/tree-checker.c
+++ b/fs/btrfs/tree-checker.c
@@ -760,18 +760,36 @@ int btrfs_check_chunk_valid(struct extent_buffer *leaf,
        u64 type;
        u64 features;
        bool mixed = false;
+       int raid_index;
+       int nparity;
+       int ncopies;
 
        length = btrfs_chunk_length(leaf, chunk);
        stripe_len = btrfs_chunk_stripe_len(leaf, chunk);
        num_stripes = btrfs_chunk_num_stripes(leaf, chunk);
        sub_stripes = btrfs_chunk_sub_stripes(leaf, chunk);
        type = btrfs_chunk_type(leaf, chunk);
+       raid_index = btrfs_bg_flags_to_raid_index(type);
+       ncopies = btrfs_raid_array[raid_index].ncopies;
+       nparity = btrfs_raid_array[raid_index].nparity;
 
        if (!num_stripes) {
                chunk_err(leaf, chunk, logical,
                          "invalid chunk num_stripes, have %u", num_stripes);
                return -EUCLEAN;
        }
+       if (num_stripes < ncopies) {
+               chunk_err(leaf, chunk, logical,
+                         "invalid chunk num_stripes < ncopies, have %u < %d",
+                         num_stripes, ncopies);
+               return -EUCLEAN;
+       }
+       if (nparity && num_stripes == nparity) {
+               chunk_err(leaf, chunk, logical,
+                         "invalid chunk num_stripes == nparity, have %u == %d",
+                         num_stripes, nparity);
+               return -EUCLEAN;
+       }
        if (!IS_ALIGNED(logical, fs_info->sectorsize)) {
                chunk_err(leaf, chunk, logical,
                "invalid chunk logical, have %llu should aligned to %u",