Re: [Linux-kernel-mentees][PATCH v2] packet: Fix undefined behavior in bit shift

[Shuah Khan]

On 6/26/19 9:25 PM, Jiunn Chang wrote:
> Shifting signed 32-bit value by 31 bits is undefined.  Changing most
> significant bit to unsigned.
>
> Changes included in v2:
>    - use subsystem specific subject lines
>    - CC required mailing lists

These version change lines don't belong in the change log.

> Signed-off-by: Jiunn Chang <c0d1n61at3@xxxxxxxxx>
> ---

Move them here.

>   include/uapi/linux/if_packet.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h
> index 467b654bd4c7..3d884d68eb30 100644
> --- a/include/uapi/linux/if_packet.h
> +++ b/include/uapi/linux/if_packet.h
> @@ -123,7 +123,7 @@ struct tpacket_auxdata {
>   /* Rx and Tx ring - header status */
>   #define TP_STATUS_TS_SOFTWARE		(1 << 29)
>   #define TP_STATUS_TS_SYS_HARDWARE	(1 << 30) /* deprecated, never set */
> -#define TP_STATUS_TS_RAW_HARDWARE	(1 << 31)
> +#define TP_STATUS_TS_RAW_HARDWARE	(1U << 31)
>   
>   /* Rx ring - feature request bits */
>   #define TP_FT_REQ_FILL_RXHASH	0x1

thanks,
-- Shuah