[v1] drm/amd/display: fix array-bounds error in dc_stream_remove_writeback()

[PATCH] drm/amd/display: fix array-bounds error in dc_stream_remove_writeback()

Posted by Hamza Mahfooz 3 years, 6 months ago

Address the following error:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function ‘dc_stream_remove_writeback’:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:55: error: array subscript [0, 0] is outside array bounds of ‘struct dc_writeback_info[1]’ [-Werror=array-bounds]
  527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
      |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc.h:1269,
                 from ./drivers/gpu/drm/amd/amdgpu/../display/dc/inc/core_types.h:29,
                 from ./drivers/gpu/drm/amd/amdgpu/../display/dc/basics/dc_common.h:29,
                 from drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:27:
./drivers/gpu/drm/amd/amdgpu/../display/dc/dc_stream.h:241:34: note: while referencing ‘writeback_info’
  241 |         struct dc_writeback_info writeback_info[MAX_DWB_PIPES];
      |

Currently, we aren't checking to see if j remains within
writeback_info[]'s bounds. So, add a check to make sure that we aren't
overflowing the buffer.

Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
---
 drivers/gpu/drm/amd/display/dc/core/dc_stream.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
index 3ca1592ce7ac..ae13887756bf 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -520,7 +520,7 @@ bool dc_stream_remove_writeback(struct dc *dc,
 	}
 
 	/* remove writeback info for disabled writeback pipes from stream */
-	for (i = 0, j = 0; i < stream->num_wb_info; i++) {
+	for (i = 0, j = 0; i < stream->num_wb_info && j < MAX_DWB_PIPES; i++) {
 		if (stream->writeback_info[i].wb_enabled) {
 			if (i != j)
 				/* trim the array */
-- 
2.37.2

Re: [PATCH] drm/amd/display: fix array-bounds error in dc_stream_remove_writeback()

Posted by Guenter Roeck 3 years, 6 months ago

On Tue, Sep 27, 2022 at 03:12:00PM -0400, Hamza Mahfooz wrote:
> Address the following error:
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function ‘dc_stream_remove_writeback’:
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:55: error: array subscript [0, 0] is outside array bounds of ‘struct dc_writeback_info[1]’ [-Werror=array-bounds]
>   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
>       |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
> In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc.h:1269,
>                  from ./drivers/gpu/drm/amd/amdgpu/../display/dc/inc/core_types.h:29,
>                  from ./drivers/gpu/drm/amd/amdgpu/../display/dc/basics/dc_common.h:29,
>                  from drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:27:
> ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc_stream.h:241:34: note: while referencing ‘writeback_info’
>   241 |         struct dc_writeback_info writeback_info[MAX_DWB_PIPES];
>       |
> 
> Currently, we aren't checking to see if j remains within
> writeback_info[]'s bounds. So, add a check to make sure that we aren't
> overflowing the buffer.
> 
> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>

With gcc 11.3, this patch doesn't fix a problem, it introduces one.

Building csky:allmodconfig ... failed
--------------
Error log:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript 1 is above array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
  527 |                                 stream->writeback_info[j] = stream->writeback_info[i];

Building mips:allmodconfig ... failed
--------------
Error log:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript [0, 0] is outside array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
  527 |                                 stream->writeback_info[j] = stream->writeback_info[i];

Building arm:allmodconfig ... failed
--------------
Error log:
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript [0, 0] is outside array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
  527 |                                 stream->writeback_info[j] = stream->writeback_info[i];

Guenter

Re: [PATCH] drm/amd/display: fix array-bounds error in dc_stream_remove_writeback()

Posted by Guenter Roeck 3 years, 6 months ago

On Wed, Oct 05, 2022 at 11:46:15PM -0700, Guenter Roeck wrote:
> On Tue, Sep 27, 2022 at 03:12:00PM -0400, Hamza Mahfooz wrote:
> > Address the following error:
> > drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function ‘dc_stream_remove_writeback’:
> > drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:55: error: array subscript [0, 0] is outside array bounds of ‘struct dc_writeback_info[1]’ [-Werror=array-bounds]
> >   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
> >       |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
> > In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc.h:1269,
> >                  from ./drivers/gpu/drm/amd/amdgpu/../display/dc/inc/core_types.h:29,
> >                  from ./drivers/gpu/drm/amd/amdgpu/../display/dc/basics/dc_common.h:29,
> >                  from drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:27:
> > ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc_stream.h:241:34: note: while referencing ‘writeback_info’
> >   241 |         struct dc_writeback_info writeback_info[MAX_DWB_PIPES];
> >       |
> > 
> > Currently, we aren't checking to see if j remains within
> > writeback_info[]'s bounds. So, add a check to make sure that we aren't
> > overflowing the buffer.
> > 
> > Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
> 
> With gcc 11.3, this patch doesn't fix a problem, it introduces one.
> 
> Building csky:allmodconfig ... failed
> --------------
> Error log:
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript 1 is above array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
>   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
> 
> Building mips:allmodconfig ... failed
> --------------
> Error log:
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript [0, 0] is outside array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
>   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
> 
> Building arm:allmodconfig ... failed
> --------------
> Error log:
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript [0, 0] is outside array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
>   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
> 

#regzbot introduced: 5d8c3e836fc2

Complete list of build failures in my test system due to this patch,
observed when building with gcc 11.3:

Build results:
	total: 149 pass: 131 fail: 18
Failed builds:
	alpha:allmodconfig
	arm:allmodconfig
	arm64:allmodconfig
	csky:allmodconfig
	i386:allyesconfig
	i386:allmodconfig
	mips:allmodconfig
	openrisc:allmodconfig
	parisc:allmodconfig
	powerpc:allmodconfig
	powerpc:ppc32_allmodconfig
	riscv32:allmodconfig
	riscv:allmodconfig
	s390:allmodconfig
	sparc64:allmodconfig
	x86_64:allyesconfig
	x86_64:allmodconfig
	xtensa:allmodconfig

Guenter

Re: [PATCH] drm/amd/display: fix array-bounds error in dc_stream_remove_writeback()

Posted by Thorsten Leemhuis 3 years, 5 months ago

[removed a lot of people from the list of recipients, as this is mainly
for Guenter]

Hi Guenter!

On 06.10.22 19:23, Guenter Roeck wrote:
> On Wed, Oct 05, 2022 at 11:46:15PM -0700, Guenter Roeck wrote:
>> On Tue, Sep 27, 2022 at 03:12:00PM -0400, Hamza Mahfooz wrote:
>>> Address the following error:
>>> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function ‘dc_stream_remove_writeback’:
>>> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:55: error: array subscript [0, 0] is outside array bounds of ‘struct dc_writeback_info[1]’ [-Werror=array-bounds]
>>>   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
>>>       |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~
>>> In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc.h:1269,
>>>                  from ./drivers/gpu/drm/amd/amdgpu/../display/dc/inc/core_types.h:29,
>>>                  from ./drivers/gpu/drm/amd/amdgpu/../display/dc/basics/dc_common.h:29,
>>>                  from drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:27:
>>> ./drivers/gpu/drm/amd/amdgpu/../display/dc/dc_stream.h:241:34: note: while referencing ‘writeback_info’
>>>   241 |         struct dc_writeback_info writeback_info[MAX_DWB_PIPES];
>>>       |
>>>
>>> Currently, we aren't checking to see if j remains within
>>> writeback_info[]'s bounds. So, add a check to make sure that we aren't
>>> overflowing the buffer.
>>>
>>> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
>>
>> With gcc 11.3, this patch doesn't fix a problem, it introduces one.
>>
>> Building csky:allmodconfig ... failed
>> --------------
>> Error log:
>> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c: In function 'dc_stream_remove_writeback':
>> drivers/gpu/drm/amd/amdgpu/../display/dc/core/dc_stream.c:527:83: error: array subscript 1 is above array bounds of 'struct dc_writeback_info[1]' [-Werror=array-bounds]
>>   527 |                                 stream->writeback_info[j] = stream->writeback_info[i];
>
> [...]
>
> #regzbot introduced: 5d8c3e836fc2

Thx for using regzbot, much appreciated. JFYI, the initial report was
your own mail you were replying to here, so a "#regzbot ^introduced:
..."  would have been more appropriate. In this case it didn't matter
anyway, as the fix didn't include a "Link:" tag to the initial report
anyway. No worries, I just have to tell regzbot about the fix manually then:

#regzbot fixed-by: faf4d8e07f5b67

Ciao, Thorsten