From 84032b6759024337a81ae5d8e23a39110381743b Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Sun, 30 Jul 2023 16:44:04 +0200 Subject: [PATCH] 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 --- fs/fat/fat_write.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) 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) -- 2.39.5