linux-kernel - [RESEND][PATCHv2] v4l2-ioctl: Give more information when device

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [day] [month] [year] [list]

Date:	Thu, 23 Jul 2015 15:28:48 -0700
From:	Laura Abbott <labbott@...oraproject.org>
To:	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	Hans Verkuil <hverkuil@...all.nl>
Cc:	Laura Abbott <labbott@...oraproject.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RESEND][PATCHv2] v4l2-ioctl: Give more information when device_caps are missing

Currently, the warning for missing device_caps gives a backtrace like so:

[<ffffffff8175c199>] dump_stack+0x45/0x57
[<ffffffff8109ad5a>] warn_slowpath_common+0x8a/0xc0
[<ffffffff8109ae8a>] warn_slowpath_null+0x1a/0x20
[<ffffffffa0237453>] v4l_querycap+0x43/0x80 [videodev]
[<ffffffffa0237734>] __video_do_ioctl+0x2a4/0x320 [videodev]
[<ffffffff812207e5>] ? do_last+0x195/0x1210
[<ffffffffa023a11e>] video_usercopy+0x22e/0x5b0 [videodev]
[<ffffffffa0237490>] ? v4l_querycap+0x80/0x80 [videodev]
[<ffffffffa023a4b5>] video_ioctl2+0x15/0x20 [videodev]
[<ffffffffa0233733>] v4l2_ioctl+0x113/0x150 [videodev]
[<ffffffff81225798>] do_vfs_ioctl+0x2f8/0x4f0
[<ffffffff8113b2d4>] ? __audit_syscall_entry+0xb4/0x110
[<ffffffff81022d7c>] ? do_audit_syscall_entry+0x6c/0x70
[<ffffffff81225a11>] SyS_ioctl+0x81/0xa0
[<ffffffff8113b526>] ? __audit_syscall_exit+0x1f6/0x2a0
[<ffffffff81763549>] system_call_fastpath+0x12/0x17

This indicates that device_caps are missing but doesn't give
much of a clue which driver is actually at fault. Improve
the warning output by showing the capabilities and the
responsible driver.

Signed-off-by: Laura Abbott <labbott@...oraproject.org>
---
I sent this out right before I went on vacation but I never saw any follow up.
---
 drivers/media/v4l2-core/v4l2-ioctl.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 85de455..ad7e929 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -1025,8 +1025,9 @@ static int v4l_querycap(const struct v4l2_ioctl_ops *ops,
 	 * Drivers MUST fill in device_caps, so check for this and
 	 * warn if it was forgotten.
 	 */
-	WARN_ON(!(cap->capabilities & V4L2_CAP_DEVICE_CAPS) ||
-		!cap->device_caps);
+	WARN(!(cap->capabilities & V4L2_CAP_DEVICE_CAPS) ||
+		!cap->device_caps, "Bad caps for driver %s, %x %x",
+		cap->driver, cap->capabilities, cap->device_caps);
 	cap->device_caps |= V4L2_CAP_EXT_PIX_FORMAT;
 
 	return ret;
-- 
2.4.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/