Re: [PATCH resend 3/5] libata-scsi: fix overflow in mode page copy

From: Tejun Heo
Date: Thu Jul 21 2016 - 17:17:31 EST


On Fri, Jul 22, 2016 at 02:41:52AM +0800, tom.ty89@xxxxxxxxx wrote:
> From: Tom Yan <tom.ty89@xxxxxxxxx>
> ata_mselect_*() would initialize a char array for storing a copy of
> the current mode page. However, if char was actually signed char,
> overflow could occur.

Do you mean sign extension?

> For example, `0xff` from def_control_mpage[] would be "truncated"
> to `-1`. This prevented ata_mselect_control() from working at all,
> since when it did the read-only bits check, there would always be
> a mismatch.

Heh, the description doesn't really make sense. Are you talking about
something like the following?

char ar[N];
int i;

i = ar[x];
if (i == 0xff)

If so, the description isn't quite right.