exfat: fix overflow issue in exfat_cluster_to_sector()

An overflow issue can occur while calculating sector in
exfat_cluster_to_sector(). It needs to cast clus's type to sector_t
before left shifting.

Fixes: 1acf1a5 ("exfat: add in-memory and on-disk structures and headers")
Cc: [email protected] # v5.7
Reviewed-by: Sungjong Seo <[email protected]>
Signed-off-by: Namjae Jeon <[email protected]>

Author: namjaejeon

fs/exfat/exfat_fs.h

@@ -371,7 +371,7 @@ static inline bool exfat_is_last_sector_in_cluster(struct exfat_sb_info *sbi,
 static inline sector_t exfat_cluster_to_sector(struct exfat_sb_info *sbi,
 		unsigned int clus)
 {
-	return ((clus - EXFAT_RESERVED_CLUSTERS) << sbi->sect_per_clus_bits) +
+	return ((sector_t)(clus - EXFAT_RESERVED_CLUSTERS) << sbi->sect_per_clus_bits) +
 		sbi->data_start_sector;
 }