diff mbox series

[10/13] media: adv7604 prevent underflow condition when reporting colorspace

Message ID 41d12c1afd6571f9cc56c1b920df6ba558d0b927.1729074076.git.mchehab+huawei@kernel.org
State Superseded
Headers show
Series Media: fix several issues on drivers | expand

Commit Message

Mauro Carvalho Chehab Oct. 16, 2024, 10:22 a.m. UTC
Currently, adv76xx_log_status() reads some date using
io_read() which may return negative values. The current logi
doesn't check such errors, causing colorspace to be reported
on a wrong way at adv76xx_log_status().

If I/O error happens there, print a different message, instead
of reporting bogus messages to userspace.

Fixes: 54450f591c99 ("[media] adv7604: driver for the Analog Devices ADV7604 video decoder")
Cc: stable@vger.kernel.org
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---
 drivers/media/i2c/adv7604.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

Comments

Mauro Carvalho Chehab Oct. 18, 2024, 5:01 a.m. UTC | #1
Em Wed, 16 Oct 2024 13:58:48 +0200
Hans Verkuil <hverkuil@xs4all.nl> escreveu:

> On 16/10/2024 13:24, Mauro Carvalho Chehab wrote:
> > Em Wed, 16 Oct 2024 12:57:53 +0200
> > Hans Verkuil <hverkuil@xs4all.nl> escreveu:
> >   
> >> On 16/10/2024 12:22, Mauro Carvalho Chehab wrote:  
> >>> Currently, adv76xx_log_status() reads some date using
> >>> io_read() which may return negative values. The current logi
> >>> doesn't check such errors, causing colorspace to be reported
> >>> on a wrong way at adv76xx_log_status().
> >>>
> >>> If I/O error happens there, print a different message, instead
> >>> of reporting bogus messages to userspace.
> >>>
> >>> Fixes: 54450f591c99 ("[media] adv7604: driver for the Analog Devices ADV7604 video decoder")
> >>> Cc: stable@vger.kernel.org    
> >>
> >> Not really a fix since this would just affect logging for debugging
> >> purposes. I would personally just drop the Fixes and Cc tag.  
> > 
> > The issue is on a VIDIOC_ ioctl, so part of media API. Ok, this is
> > used only for debugging purposes and should, instead be implemented
> > via debugfs, etc, but, in summary: it is what it is: part of the V4L2
> > uAPI.  
> 
> The ioctl, yes, but what it logs to the kernel log isn't part of the ABI.
> That can change.

Sure, logs can change, but this is an user-visible bug.

> I think it is overkill to send this to stable for an old chip that almost
> nobody uses, and that requires an i2c read to go wrong for it to produce
> a wrong debug message. It seems an unnecessary waste of time.

Agreed. Will drop cc stable.

> > 
> > -
> > 
> > Now, the question about what should have Fixes: tag and what
> > shouldn't is a different matter. I've saw long discussions about
> > that at the kernel mailing lists. In the particular case of y2038,
> > I'm pretty sure I saw some of them with Fixes tag on it.  
> 
> But patch 13/13 doesn't affect the operation either, again it is just
> an incorrect log message that can only go wrong if Pulse-Eight still
> sells that device in 2038 with a firmware build date >= 2038. 

> And v6.12 is guaranteed to be EOL in 2038 :-)

We can't count on it. Civil infrastructure is now working with a 10 years
SLTS:

	https://www.linuxfoundation.org/press/civil-infrastructure-platform-expands-slt-stable-kernel-program

I heard somewhere that having a 15 years or 20 years stable Kernel is a
need for certain usages.

Even commercial distros have a minimum of 10 years as LTS.

Suse is now working with a 13-years support. Both Canonical and Red Hat
announced a 12-years ELTS support. As they usually takes the last year's 
LTS Kernel, it means support will end with a 14 years old Kernel (so, 
support will end in 2037 or 2038 if they release an LTS distro next year),
and don't decide to extend it further.

I also heard during LPC that there's an increased pressure from Linux
customers from commercial distros to extend it even further.


Thanks,
Mauro
diff mbox series

Patch

diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c
index 48230d5109f0..272945a878b3 100644
--- a/drivers/media/i2c/adv7604.c
+++ b/drivers/media/i2c/adv7604.c
@@ -2519,10 +2519,10 @@  static int adv76xx_log_status(struct v4l2_subdev *sd)
 	const struct adv76xx_chip_info *info = state->info;
 	struct v4l2_dv_timings timings;
 	struct stdi_readback stdi;
-	u8 reg_io_0x02 = io_read(sd, 0x02);
+	int ret;
+	u8 reg_io_0x02;
 	u8 edid_enabled;
 	u8 cable_det;
-
 	static const char * const csc_coeff_sel_rb[16] = {
 		"bypassed", "YPbPr601 -> RGB", "reserved", "YPbPr709 -> RGB",
 		"reserved", "RGB -> YPbPr601", "reserved", "RGB -> YPbPr709",
@@ -2621,13 +2621,21 @@  static int adv76xx_log_status(struct v4l2_subdev *sd)
 	v4l2_info(sd, "-----Color space-----\n");
 	v4l2_info(sd, "RGB quantization range ctrl: %s\n",
 			rgb_quantization_range_txt[state->rgb_quantization_range]);
-	v4l2_info(sd, "Input color space: %s\n",
-			input_color_space_txt[reg_io_0x02 >> 4]);
-	v4l2_info(sd, "Output color space: %s %s, alt-gamma %s\n",
-			(reg_io_0x02 & 0x02) ? "RGB" : "YCbCr",
-			(((reg_io_0x02 >> 2) & 0x01) ^ (reg_io_0x02 & 0x01)) ?
-				"(16-235)" : "(0-255)",
-			(reg_io_0x02 & 0x08) ? "enabled" : "disabled");
+
+	ret = io_read(sd, 0x02);
+	if (ret < 0) {
+		v4l2_info(sd, "Can't read Input/Output color space\n");
+	} else {
+		reg_io_0x02 = ret;
+
+		v4l2_info(sd, "Input color space: %s\n",
+				input_color_space_txt[reg_io_0x02 >> 4]);
+		v4l2_info(sd, "Output color space: %s %s, alt-gamma %s\n",
+				(reg_io_0x02 & 0x02) ? "RGB" : "YCbCr",
+				(((reg_io_0x02 >> 2) & 0x01) ^ (reg_io_0x02 & 0x01)) ?
+					"(16-235)" : "(0-255)",
+				(reg_io_0x02 & 0x08) ? "enabled" : "disabled");
+	}
 	v4l2_info(sd, "Color space conversion: %s\n",
 			csc_coeff_sel_rb[cp_read(sd, info->cp_csc) >> 4]);