From: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Date: Sun, 30 Jul 2023 14:44:04 +0000 (+0200)
Subject: fs: fat: avoid multiplication overflow
X-Git-Tag: v2025.01-rc5-pxa1908~847^2~36^2~5
X-Git-Url: http://git.dujemihanovic.xyz/img/static/git-logo.png?a=commitdiff_plain;h=84032b6759024337a81ae5d8e23a39110381743b;p=u-boot.git

fs: fat: avoid multiplication overflow

The product of two 32 bit integers is a 32 bit integer. Hence
clustcount * bytesperclust may overflow on > 4 GiB devices.

Change the type of clustcount.

Fixes: cb8af8af5ba0 ("fs: fat: support write with non-zero offset")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index a6294419b8..8b5d669b00 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -690,8 +690,8 @@ get_set_cluster(fsdata *mydata, __u32 clustnum, loff_t pos, __u8 *buffer,
 	static u8 *tmpbuf_cluster;
 	unsigned int bytesperclust = mydata->clust_size * mydata->sect_size;
 	__u32 startsect;
-	loff_t wsize;
-	int clustcount, i, ret;
+	loff_t clustcount, wsize;
+	int i, ret;
 
 	*gotsize = 0;
 	if (!size)