From 43946b70494beefe40ec1b2ba4744c0f294d7736 Mon Sep 17 00:00:00 2001
From: Namjae Jeon <namjae.jeon@samsung.com>
Date: Fri Jul  3 11:16:32 2020 +0900
Subject: [PATCH] exfat: fix overflow issue in exfat_cluster_to_sector() 
Git-commit: 43946b70494beefe40ec1b2ba4744c0f294d7736
References: git-fixes
Patch-mainline: v5.8-rc7

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: 1acf1a564b60 ("exfat: add in-memory and on-disk structures and headers")
Cc: stable@vger.kernel.org # v5.7
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>

diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 7579cd3..75c7bdb 100644
--- a/fs/exfat/exfat_fs.h
+++ b/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;
 }