From: Peng Fan Date: Fri, 11 Sep 2015 13:41:47 +0000 (+0800) Subject: mtd: blktrans: fix multiplication overflow X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=2ce401d56b36a7492b26646b94d1fe9194880a1a;p=linux-beck.git mtd: blktrans: fix multiplication overflow In drivers/mtd/mtd_blkdevs.c: 406 set_capacity(gd, (new->size * tr->blksize) >> 9); The type of new->size is unsigned long and the type of tr->blksize is int, the result of 'new->size * tr->blksize' may exceed ULONG_MAX on 32bit machines. I use nand chip MT29F32G08CBADBWP which is 4GB and the parameters passed to kernel is 'mtdparts=gpmi-nand:-(user)', the whole nand chip will be treated as a 4GB mtd partition. new->size is 0x800000 and tr->blksize is 0x200, 'new->size * tr->blksize' however is 0. This is what we do not want to see. Using type cast u64 to fix the multiplication overflow issue. Signed-off-by: Peng Fan Cc: David Woodhouse Signed-off-by: Brian Norris --- diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c index 44dc965a2f7c..cb47d79f4c21 100644 --- a/drivers/mtd/mtd_blkdevs.c +++ b/drivers/mtd/mtd_blkdevs.c @@ -399,7 +399,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new) snprintf(gd->disk_name, sizeof(gd->disk_name), "%s%d", tr->name, new->devnum); - set_capacity(gd, (new->size * tr->blksize) >> 9); + set_capacity(gd, ((u64)new->size * tr->blksize) >> 9); /* Create the request queue */ spin_lock_init(&new->queue_lock);