1 files changed, 11 insertions, 0 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 1484a087bba0..32e3ecb35cd7 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1997,6 +1997,17 @@ static int ext4_fill_super (struct super_block *sb, void *data, int silent)
 
         if (EXT4_BLOCKS_PER_GROUP(sb) == 0)
                 goto cantfind_ext4;
+
+        /* ensure blocks_count calculation below doesn't sign-extend */
+        if (ext4_blocks_count(es) + EXT4_BLOCKS_PER_GROUP(sb) <
+            le32_to_cpu(es->s_first_data_block) + 1) {
+                printk(KERN_WARNING "EXT4-fs: bad geometry: block count %llu, "
+                       "first data block %u, blocks per group %lu\n",
+                        ext4_blocks_count(es),
+                        le32_to_cpu(es->s_first_data_block),
+                        EXT4_BLOCKS_PER_GROUP(sb));
+                goto failed_mount;
+        }
         blocks_count = (ext4_blocks_count(es) -
                         le32_to_cpu(es->s_first_data_block) +
                         EXT4_BLOCKS_PER_GROUP(sb) - 1);