ext4: add check for wraparound in ext4_data_block_valid()

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

diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c
index dc79b75..4df8621 100644 (file)
--- 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) {