linux-kernel - [PATCH 5.16 0299/1017] media: v4l: Avoid unaligned access warnings when printing 4cc modifiers

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Message-Id: <20220405070403.150447315@linuxfoundation.org>
Date:   Tue,  5 Apr 2022 09:20:12 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.16 0299/1017] media: v4l: Avoid unaligned access warnings when printing 4cc modifiers

From: Sakari Ailus <sakari.ailus@...ux.intel.com>

[ Upstream commit 24bb30c8c894ec7213ad810b46e2a6a4c12136c1 ]

Pointers V4L2 pixelformat and dataformat fields in a few packed structs
are directly passed to printk family of functions. This could result in an
unaligned access albeit no such possibility appears to exist at the
moment i.e. this clang warning appears to be a false positive.

Address the warning by copying the pixelformat or dataformat value to a
local variable first.

Reported-by: kernel test robot <lkp@...el.com>
Fixes: e927e1e0f0dd ("v4l: ioctl: Use %p4cc printk modifier to print FourCC codes")
Signed-off-by: Sakari Ailus <sakari.ailus@...ux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/v4l2-core/v4l2-ioctl.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 69b74d0e8a90..059d6debb25d 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -279,8 +279,8 @@ static void v4l_print_format(const void *arg, bool write_only)
 	const struct v4l2_vbi_format *vbi;
 	const struct v4l2_sliced_vbi_format *sliced;
 	const struct v4l2_window *win;
-	const struct v4l2_sdr_format *sdr;
 	const struct v4l2_meta_format *meta;
+	u32 pixelformat;
 	u32 planes;
 	unsigned i;
 
@@ -299,8 +299,9 @@ static void v4l_print_format(const void *arg, bool write_only)
 	case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
 	case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
 		mp = &p->fmt.pix_mp;
+		pixelformat = mp->pixelformat;
 		pr_cont(", width=%u, height=%u, format=%p4cc, field=%s, colorspace=%d, num_planes=%u, flags=0x%x, ycbcr_enc=%u, quantization=%u, xfer_func=%u\n",
-			mp->width, mp->height, &mp->pixelformat,
+			mp->width, mp->height, &pixelformat,
 			prt_names(mp->field, v4l2_field_names),
 			mp->colorspace, mp->num_planes, mp->flags,
 			mp->ycbcr_enc, mp->quantization, mp->xfer_func);
@@ -343,14 +344,15 @@ static void v4l_print_format(const void *arg, bool write_only)
 		break;
 	case V4L2_BUF_TYPE_SDR_CAPTURE:
 	case V4L2_BUF_TYPE_SDR_OUTPUT:
-		sdr = &p->fmt.sdr;
-		pr_cont(", pixelformat=%p4cc\n", &sdr->pixelformat);
+		pixelformat = p->fmt.sdr.pixelformat;
+		pr_cont(", pixelformat=%p4cc\n", &pixelformat);
 		break;
 	case V4L2_BUF_TYPE_META_CAPTURE:
 	case V4L2_BUF_TYPE_META_OUTPUT:
 		meta = &p->fmt.meta;
+		pixelformat = meta->dataformat;
 		pr_cont(", dataformat=%p4cc, buffersize=%u\n",
-			&meta->dataformat, meta->buffersize);
+			&pixelformat, meta->buffersize);
 		break;
 	}
 }
-- 
2.34.1