ext4: add check for wraparound in ext4_data_block_valid()

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index dc79b75d8f70..4df8621ec31c 100644
--- a/fs/ext4/block_validity.c
+++ b/fs/ext4/block_validity.c
@@ -228,6 +228,7 @@ int ext4_data_block_valid(struct ext4_sb_info *sbi, ext4_fsblk_t start_blk,
         struct rb_node *n = sbi->system_blks.rb_node;
 
         if ((start_blk <= le32_to_cpu(sbi->s_es->s_first_data_block)) ||
+            (start_blk + count < start_blk) ||
             (start_blk + count > ext4_blocks_count(sbi->s_es)))
                 return 0;
         while (n) {