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USB: sisusbvga: Fix a potential UB casued by left shifting a negative value

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[ 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>
This commit is contained in:
Changming Liu 2020-07-11 00:30:18 -04:00 committed by Greg Kroah-Hartman
parent e77f71c634
commit 7aac56d8b0
1 changed files with 1 additions and 1 deletions
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2
drivers/usb/misc/sisusbvga/sisusb.c
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@ -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