From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from smtp-vbr1.xs4all.nl ([194.109.24.21]:2422 "EHLO smtp-vbr1.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751434AbaGZQDJ (ORCPT ); Sat, 26 Jul 2014 12:03:09 -0400 Message-ID: <53D3D133.7000103@xs4all.nl> Date: Sat, 26 Jul 2014 18:02:59 +0200 From: Hans Verkuil MIME-Version: 1.0 To: Linux Media Mailing List , =?UTF-8?B?RnJhbmsgU2Now6RmZXI=?= Subject: [PATCH for v3.17] v4l2-ctrls: fix rounding calculation Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: Commit 958c7c7e65 ("[media] v4l2-ctrls: fix corner case in round-to-range code") broke controls that use a negative range. The cause was a s32/u32 mixup: ctrl->step is unsigned while all others are signed. So the result type of the expression '(ctrl)->maximum - ((ctrl)->step / 2)' became unsigned, making 'val >= (ctrl)->maximum - ((ctrl)->step / 2)' true, since '((u32)-128) > 128' (if val = -128, maximum = 128 and step = 1). So carefully cast (step / 2) to s32. There was one cast of step to s32 where it should have been u32 because both offset and step are unsigned, so casting to signed makes no sense there. You do need a cast to u32 there, because otherwise architectures that have no 64-bit division start complaining (step is a u64). Signed-off-by: Hans Verkuil Reported-by: Frank Schäfer diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c index 2d8ced8..9d0c7a1 100644 --- a/drivers/media/v4l2-core/v4l2-ctrls.c +++ b/drivers/media/v4l2-core/v4l2-ctrls.c @@ -1347,14 +1347,14 @@ static void std_log(const struct v4l2_ctrl *ctrl) ({ \ offset_type offset; \ if ((ctrl)->maximum >= 0 && \ - val >= (ctrl)->maximum - ((ctrl)->step / 2)) \ + val >= (ctrl)->maximum - (s32)((ctrl)->step / 2)) \ val = (ctrl)->maximum; \ else \ - val += (ctrl)->step / 2; \ + val += (s32)((ctrl)->step / 2); \ val = clamp_t(typeof(val), val, \ (ctrl)->minimum, (ctrl)->maximum); \ offset = (val) - (ctrl)->minimum; \ - offset = (ctrl)->step * (offset / (s32)(ctrl)->step); \ + offset = (ctrl)->step * (offset / (u32)(ctrl)->step); \ val = (ctrl)->minimum + offset; \ 0; \ }) @@ -1376,10 +1376,10 @@ static int std_validate(const struct v4l2_ctrl *ctrl, u32 idx, * the u64 divide that needs special care. */ val = ptr.p_s64[idx]; - if (ctrl->maximum >= 0 && val >= ctrl->maximum - ctrl->step / 2) + if (ctrl->maximum >= 0 && val >= ctrl->maximum - (s64)(ctrl->step / 2)) val = ctrl->maximum; else - val += ctrl->step / 2; + val += (s64)(ctrl->step / 2); val = clamp_t(s64, val, ctrl->minimum, ctrl->maximum); offset = val - ctrl->minimum; do_div(offset, ctrl->step);