* grub-core/fs/btrfs.c: Avoid divisions by zero.

diff --git a/ChangeLog b/ChangeLog
index a708ca28a2526e044c4a7cde3ab05dded6343643..8e38fdd4293862cb870bcdaa5b8e8e8242294e55 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2015-01-20  Vladimir Serbinenko  <phcoder@gmail.com>
+
+       * grub-core/fs/btrfs.c: Avoid divisions by zero.
+
 2015-01-20  Vladimir Serbinenko  <phcoder@gmail.com>
 
        * grub-core/lib/pbkdf2.c (grub_crypto_pbkdf2): Check that hash len is not 0.

diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 95a8fa6b3979555333459753ff44cac9d4c61e20..9cffa91fafb081c4a161b38e0710b28c19f48aa0 100644 (file)
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -680,6 +680,8 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
        grub_uint64_t stripen;
        grub_uint64_t stripe_offset;
        grub_uint64_t off = addr - grub_le_to_cpu64 (key->offset);
+       grub_uint64_t chunk_stripe_length;
+       grub_uint16_t nstripes;
        unsigned redundancy = 1;
        unsigned i, j;
 
@@ -690,15 +692,17 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
                               "couldn't find the chunk descriptor");
          }
 
+       nstripes = grub_le_to_cpu16 (chunk->nstripes) ? : 1;
+       chunk_stripe_length = grub_le_to_cpu64 (chunk->stripe_length) ? : 512;
        grub_dprintf ("btrfs", "chunk 0x%" PRIxGRUB_UINT64_T
                      "+0x%" PRIxGRUB_UINT64_T
                      " (%d stripes (%d substripes) of %"
                      PRIxGRUB_UINT64_T ")\n",
                      grub_le_to_cpu64 (key->offset),
                      grub_le_to_cpu64 (chunk->size),
-                     grub_le_to_cpu16 (chunk->nstripes),
+                     nstripes,
                      grub_le_to_cpu16 (chunk->nsubstripes),
-                     grub_le_to_cpu64 (chunk->stripe_length));
+                     chunk_stripe_length);
 
        switch (grub_le_to_cpu64 (chunk->type)
                & ~GRUB_BTRFS_CHUNK_TYPE_BITS_DONTCARE)
@@ -708,8 +712,10 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
              grub_uint64_t stripe_length;
              grub_dprintf ("btrfs", "single\n");
              stripe_length = grub_divmod64 (grub_le_to_cpu64 (chunk->size),
-                                            grub_le_to_cpu16 (chunk->nstripes),
+                                            nstripes,
                                             NULL);
+             if (stripe_length == 0)
+               stripe_length = 512;
              stripen = grub_divmod64 (off, stripe_length, &stripe_offset);
              csize = (stripen + 1) * stripe_length - off;
              break;
@@ -730,33 +736,34 @@ grub_btrfs_read_logical (struct grub_btrfs_data *data, grub_disk_addr_t addr,
              grub_uint64_t low;
              grub_dprintf ("btrfs", "RAID0\n");
              middle = grub_divmod64 (off,
-                                     grub_le_to_cpu64 (chunk->stripe_length),
+                                     chunk_stripe_length,
                                      &low);
 
-             high = grub_divmod64 (middle, grub_le_to_cpu16 (chunk->nstripes),
+             high = grub_divmod64 (middle, nstripes,
                                    &stripen);
              stripe_offset =
-               low + grub_le_to_cpu64 (chunk->stripe_length) * high;
-             csize = grub_le_to_cpu64 (chunk->stripe_length) - low;
+               low + chunk_stripe_length * high;
+             csize = chunk_stripe_length - low;
              break;
            }
          case GRUB_BTRFS_CHUNK_TYPE_RAID10:
            {
              grub_uint64_t middle, high;
              grub_uint64_t low;
+             grub_uint16_t nsubstripes;
+             nsubstripes = grub_le_to_cpu16 (chunk->nsubstripes) ? : 1;
              middle = grub_divmod64 (off,
-                                     grub_le_to_cpu64 (chunk->stripe_length),
+                                     chunk_stripe_length,
                                      &low);
 
              high = grub_divmod64 (middle,
-                                   grub_le_to_cpu16 (chunk->nstripes)
-                                   / grub_le_to_cpu16 (chunk->nsubstripes),
+                                   nstripes / nsubstripes ? : 1,
                                    &stripen);
-             stripen *= grub_le_to_cpu16 (chunk->nsubstripes);
-             redundancy = grub_le_to_cpu16 (chunk->nsubstripes);
-             stripe_offset = low + grub_le_to_cpu64 (chunk->stripe_length)
+             stripen *= nsubstripes;
+             redundancy = nsubstripes;
+             stripe_offset = low + chunk_stripe_length
                * high;
-             csize = grub_le_to_cpu64 (chunk->stripe_length) - low;
+             csize = chunk_stripe_length - low;
              break;
            }
          default: