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[4.19,050/125] USB: sisusbvga: Fix a potential UB casued by left shifting a negative value

Message ID 20200901150937.001525313@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Sept. 1, 2020, 3:10 p.m. UTC 
From: Changming Liu <charley.ashbringer@gmail.com>

[ Upstream commit 2b53a19284f537168fb506f2f40d7fda40a01162 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/misc/sisusbvga/sisusb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/drivers/usb/misc/sisusbvga/sisusb.c b/drivers/usb/misc/sisusbvga/sisusb.c
index 6376be1f5fd22..4877bf82ad395 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