Re: dm raid: pointer math issue in super_sync()
From: Mike Snitzer <hidden>
Date: 2014-10-21 12:48:26
Also in:
dm-devel, kernel-janitors
On Tue, Oct 21 2014 at 8:43am -0400, Dan Carpenter [off-list ref] wrote:
quoted hunk ↗ jump to hunk
"sb" is a dm_raid_superblock struct pointer so the pointer math doesn't work and we will end up corrupting memory. Signed-off-by: Dan Carpenter <redacted>diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index b802644..a7cb9dd 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c@@ -826,7 +826,7 @@ static void super_sync(struct mddev *mddev, struct md_rdev *rdev) test_bit(Faulty, &(rs->dev[i].rdev.flags))) failed_devices |= (1ULL << i); - memset(sb + sizeof(*sb), 0, rdev->sb_size - sizeof(*sb)); + memset(sb + 1, 0, rdev->sb_size - sizeof(*sb)); sb->magic = cpu_to_le32(DM_RAID_MAGIC); sb->features = cpu_to_le32(0); /* No features yet */
Not following... sizeof(*sb) != sizeof(sb). So I'm not seeing a problem. Nor am I seeing how you think sb + 1 is equivalent to what Heinz intended (zero the memory following the sizeof(struct dm_raid_superblock)).