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From: Greg KH <gregkh@linuxfoundation.org>
To: Changming Liu <liu.changm@northeastern.edu>
Cc: "thomas@winischhofer.net" <thomas@winischhofer.net>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>
Subject: Re: [PATCH] USB: sisusbvga: Fix left shifting a possible negative value
Date: Thu, 21 May 2020 09:36:27 +0200	[thread overview]
Message-ID: <20200521073627.GB2579717@kroah.com> (raw)
In-Reply-To: <BL0PR06MB45483EF82A54B8751524A2E7E5B60@BL0PR06MB4548.namprd06.prod.outlook.com>

On Wed, May 20, 2020 at 06:06:50PM +0000, Changming Liu wrote:
> The char buffer buf, accepts user data which might be negative value and
> the content is left shifted to form an unsigned integer.
> 
> Since left shifting a negative value is undefined behavior, thus change
> the char to u8 to fix this
> 
> Signed-off-by: Changming Liu <liu.changm@northeastern.edu>
> ---
>  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 fc8a5da4a07c..0734e6dd9386 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];

Do we also need to change the kernbuffer variable from char* to be u8*
as the same time to solve the same potential issue?

thanks,

greg k-h

  reply	other threads:[~2020-05-21  7:36 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-20 18:06 [PATCH] USB: sisusbvga: Fix left shifting a possible negative value Changming Liu
2020-05-21  7:36 ` Greg KH [this message]
2020-05-21 17:56   ` Changming Liu
2020-05-22  7:24     ` Greg KH
2020-05-22 19:14       ` Changming Liu
2020-05-23  6:13         ` Greg KH
2020-06-05 22:13           ` Changming Liu
2020-06-14  9:37             ` Greg KH
  -- strict thread matches above, loose matches on Subject: below --
2020-05-20 16:37 Changming Liu
2020-05-20 16:47 ` Greg KH
2020-05-20 18:14   ` Changming Liu

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