mtd: diskonchip: Cast an operand to prevent potential overflow

There may be a potential integer overflow issue in inftl_partscan().
parts[0].size is defined as "uint64_t"  while mtd->erasesize and
ip->firstUnit are defined as 32-bit unsigned integer. The result of
the calculation will be limited to 32 bits without correct casting.

Fixes: 1da177e ("Linux-2.6.12-rc2")
Signed-off-by: Zichen Xie <[email protected]>
Cc: [email protected]
Signed-off-by: Miquel Raynal <[email protected]>

Author: Gax-c

drivers/mtd/nand/raw/diskonchip.c

@@ -1098,7 +1098,7 @@ static inline int __init inftl_partscan(struct mtd_info *mtd, struct mtd_partiti
 		    (i == 0) && (ip->firstUnit > 0)) {
 			parts[0].name = " DiskOnChip IPL / Media Header partition";
 			parts[0].offset = 0;
-			parts[0].size = mtd->erasesize * ip->firstUnit;
+			parts[0].size = (uint64_t)mtd->erasesize * ip->firstUnit;
 			numparts = 1;
 		}