From 2b53a19284f537168fb506f2f40d7fda40a01162 Mon Sep 17 00:00:00 2001
From: Changming Liu <charley.ashbringer@gmail.com>
Date: Sat, 11 Jul 2020 00:30:18 -0400
Subject: [PATCH] USB: sisusbvga: Fix a potential UB casued by left shifting a negative value
Git-commit: 2b53a19284f537168fb506f2f40d7fda40a01162
Patch-mainline: v5.9-rc1
References: git-fixes
The char buffer buf, receives data directly from user space,
so its content might be negative and its elements are left
shifted to form an unsigned integer.
Since left shifting a negative value is undefined behavior, thus
change the char to u8 to elimintate this UB.
Signed-off-by: Changming Liu <charley.ashbringer@gmail.com>
Link: https://lore.kernel.org/r/20200711043018.928-1-charley.ashbringer@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/usb/misc/sisusbvga/sisusb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/misc/sisusbvga/sisusb.c b/drivers/usb/misc/sisusbvga/sisusb.c
index 88c4975e303d..f08de33d9ff3 100644
--- a/drivers/usb/misc/sisusbvga/sisusb.c
+++ b/drivers/usb/misc/sisusbvga/sisusb.c
@@ -761,7 +761,7 @@ static int sisusb_write_mem_bulk(struct sisusb_usb_data *sisusb, u32 addr,
u8 swap8, fromkern = kernbuffer ? 1 : 0;
u16 swap16;
u32 swap32, flag = (length >> 28) & 1;
- char buf[4];
+ u8 buf[4];
/* if neither kernbuffer not userbuffer are given, assume
* data in obuf
--
2.16.4