fs/partitions: Validate map_count in Mac partition tables

Validate number of blocks in map and remove redundant variable.

Signed-off-by: Timo Warns <warns@pre-sense.de>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 8 deletions

diff --git a/fs/partitions/mac.c b/fs/partitions/mac.c
index 68d6a216ee79..11f688bd76c5 100644
--- a/fs/partitions/mac.c
+++ b/fs/partitions/mac.c
@@ -29,10 +29,9 @@ static inline void mac_fix_string(char *stg, int len)
 
 int mac_partition(struct parsed_partitions *state)
 {
-        int slot = 1;
         Sector sect;
         unsigned char *data;
-        int blk, blocks_in_map;
+        int slot, blocks_in_map;
         unsigned secsize;
 #ifdef CONFIG_PPC_PMAC
         int found_root = 0;
@@ -59,10 +58,14 @@ int mac_partition(struct parsed_partitions *state)
                 put_dev_sector(sect);
                 return 0;               /* not a MacOS disk */
         }
-        strlcat(state->pp_buf, " [mac]", PAGE_SIZE);
         blocks_in_map = be32_to_cpu(part->map_count);
-        for (blk = 1; blk <= blocks_in_map; ++blk) {
-                int pos = blk * secsize;
+        if (blocks_in_map < 0 || blocks_in_map >= DISK_MAX_PARTS) {
+                put_dev_sector(sect);
+                return 0;
+        }
+        strlcat(state->pp_buf, " [mac]", PAGE_SIZE);
+        for (slot = 1; slot <= blocks_in_map; ++slot) {
+                int pos = slot * secsize;
                 put_dev_sector(sect);
                 data = read_part_sector(state, pos/512, &sect);
                 if (!data)
@@ -113,13 +116,11 @@ int mac_partition(struct parsed_partitions *state)
                         }
 
                         if (goodness > found_root_goodness) {
-                                found_root = blk;
+                                found_root = slot;
                                 found_root_goodness = goodness;
                         }
                 }
 #endif /* CONFIG_PPC_PMAC */
-
-                ++slot;
         }
 #ifdef CONFIG_PPC_PMAC
         if (found_root_goodness)