From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:60984 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965219AbeE1KMx (ORCPT ); Mon, 28 May 2018 06:12:53 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Laurent Pinchart , Sakari Ailus , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 3.18 162/185] media: s3c-camif: fix out-of-bounds array access Date: Mon, 28 May 2018 12:03:23 +0200 Message-Id: <20180528100111.871074495@linuxfoundation.org> In-Reply-To: <20180528100050.700971285@linuxfoundation.org> References: <20180528100050.700971285@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Arnd Bergmann [ Upstream commit a398e043637a4819a0e96467bfecaabf3224dd62 ] While experimenting with older compiler versions, I ran into a warning that no longer shows up on gcc-4.8 or newer: drivers/media/platform/s3c-camif/camif-capture.c: In function '__camif_subdev_try_format': drivers/media/platform/s3c-camif/camif-capture.c:1265:25: error: array subscript is below array bounds This is an off-by-one bug, leading to an access before the start of the array, while newer compilers silently assume this undefined behavior cannot happen and leave the loop at index 0 if no other entry matches. As Sylvester explains, we actually need to ensure that the value is within the range, so this reworks the loop to be easier to parse correctly, and an additional check to fall back on the first format value for any unexpected input. I found an existing gcc bug for it and added a reduced version of the function there. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69249#c3 Fixes: babde1c243b2 ("[media] V4L: Add driver for S3C24XX/S3C64XX SoC series camera interface") Signed-off-by: Arnd Bergmann Reviewed-by: Laurent Pinchart Acked-by: Sakari Ailus Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/media/platform/s3c-camif/camif-capture.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/media/platform/s3c-camif/camif-capture.c +++ b/drivers/media/platform/s3c-camif/camif-capture.c @@ -1280,16 +1280,17 @@ static void __camif_subdev_try_format(st { const struct s3c_camif_variant *variant = camif->variant; const struct vp_pix_limits *pix_lim; - int i = ARRAY_SIZE(camif_mbus_formats); + unsigned int i; /* FIXME: constraints against codec or preview path ? */ pix_lim = &variant->vp_pix_limits[VP_CODEC]; - while (i-- >= 0) + for (i = 0; i < ARRAY_SIZE(camif_mbus_formats); i++) if (camif_mbus_formats[i] == mf->code) break; - mf->code = camif_mbus_formats[i]; + if (i == ARRAY_SIZE(camif_mbus_formats)) + mf->code = camif_mbus_formats[0]; if (pad == CAMIF_SD_PAD_SINK) { v4l_bound_align_image(&mf->width, 8, CAMIF_MAX_PIX_WIDTH,