diff mbox

[FFmpeg-devel] avutil/hwcontext_vaapi: fix SEGV in vaTerminate when vaInitialize fails

Message ID 20170202172913.36256-1-ffmpeg@tmm1.net
State Accepted
Commit 3606602f1137552ea54f2c259eb140c1e3c026d4
Headers show

Commit Message

Aman Gupta Feb. 2, 2017, 5:29 p.m. UTC
From: Aman Gupta <aman@tmm1.net>

Program terminated with signal SIGSEGV, Segmentation fault.
    opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
---
 libavutil/hwcontext_vaapi.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

Comments

Aman Gupta Feb. 2, 2017, 8:05 p.m. UTC | #1
On Thu, Feb 2, 2017 at 9:29 AM, Aman Gupta <ffmpeg@tmm1.net> wrote:

> From: Aman Gupta <aman@tmm1.net>
>
> Program terminated with signal SIGSEGV, Segmentation fault.
>     opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
>

Looks like my editor ate the gdb backtrace I had pasted. Will resubmit with
the commit message fixed if no one has objects to the diff.


> ---
>  libavutil/hwcontext_vaapi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
> index 6176bdc..0051acb 100644
> --- a/libavutil/hwcontext_vaapi.c
> +++ b/libavutil/hwcontext_vaapi.c
> @@ -961,14 +961,13 @@ static int vaapi_device_create(AVHWDeviceContext
> *ctx, const char *device,
>          return AVERROR(EINVAL);
>      }
>
> -    hwctx->display = display;
> -
>      vas = vaInitialize(display, &major, &minor);
>      if (vas != VA_STATUS_SUCCESS) {
>          av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
>                 "connection: %d (%s).\n", vas, vaErrorStr(vas));
>          return AVERROR(EIO);
>      }
> +    hwctx->display = display;
>      av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
>             "version %d.%d\n", major, minor);
>
> --
> 2.10.1 (Apple Git-78)
>
>
Mark Thompson Feb. 2, 2017, 10:25 p.m. UTC | #2
On 02/02/17 20:05, Aman Gupta wrote:
> On Thu, Feb 2, 2017 at 9:29 AM, Aman Gupta <ffmpeg@tmm1.net> wrote:
> 
>> From: Aman Gupta <aman@tmm1.net>
>>
>> Program terminated with signal SIGSEGV, Segmentation fault.
>>     opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
>>
> 
> Looks like my editor ate the gdb backtrace I had pasted. Will resubmit with
> the commit message fixed if no one has objects to the diff.

Patch LGTM (oops).  If you want to make a new version with the commit message adjusted to your satisfaction then it can be applied immediately.

Thanks,

- Mark

>> ---
>>  libavutil/hwcontext_vaapi.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
>> index 6176bdc..0051acb 100644
>> --- a/libavutil/hwcontext_vaapi.c
>> +++ b/libavutil/hwcontext_vaapi.c
>> @@ -961,14 +961,13 @@ static int vaapi_device_create(AVHWDeviceContext
>> *ctx, const char *device,
>>          return AVERROR(EINVAL);
>>      }
>>
>> -    hwctx->display = display;
>> -
>>      vas = vaInitialize(display, &major, &minor);
>>      if (vas != VA_STATUS_SUCCESS) {
>>          av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
>>                 "connection: %d (%s).\n", vas, vaErrorStr(vas));
>>          return AVERROR(EIO);
>>      }
>> +    hwctx->display = display;
>>      av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
>>             "version %d.%d\n", major, minor);
>>
>> --
>> 2.10.1 (Apple Git-78)
wm4 Feb. 3, 2017, 5:45 a.m. UTC | #3
On Thu,  2 Feb 2017 09:29:13 -0800
Aman Gupta <ffmpeg@tmm1.net> wrote:

> From: Aman Gupta <aman@tmm1.net>
> 
> Program terminated with signal SIGSEGV, Segmentation fault.
>     opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
> ---
>  libavutil/hwcontext_vaapi.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
> index 6176bdc..0051acb 100644
> --- a/libavutil/hwcontext_vaapi.c
> +++ b/libavutil/hwcontext_vaapi.c
> @@ -961,14 +961,13 @@ static int vaapi_device_create(AVHWDeviceContext *ctx, const char *device,
>          return AVERROR(EINVAL);
>      }
>  
> -    hwctx->display = display;
> -
>      vas = vaInitialize(display, &major, &minor);
>      if (vas != VA_STATUS_SUCCESS) {
>          av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
>                 "connection: %d (%s).\n", vas, vaErrorStr(vas));
>          return AVERROR(EIO);
>      }
> +    hwctx->display = display;
>      av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
>             "version %d.%d\n", major, minor);
>  

Would that mean it doesn't free the display that was created with
vaGetDisplay? Is that right?

In my experiments, calling vaTerminate right after vaGetDisplay works
just fine.
Mark Thompson Feb. 3, 2017, 8:19 p.m. UTC | #4
On 03/02/17 05:45, wm4 wrote:
> On Thu,  2 Feb 2017 09:29:13 -0800
> Aman Gupta <ffmpeg@tmm1.net> wrote:
> 
>> From: Aman Gupta <aman@tmm1.net>
>>
>> Program terminated with signal SIGSEGV, Segmentation fault.
>>     opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
>> ---
>>  libavutil/hwcontext_vaapi.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
>> index 6176bdc..0051acb 100644
>> --- a/libavutil/hwcontext_vaapi.c
>> +++ b/libavutil/hwcontext_vaapi.c
>> @@ -961,14 +961,13 @@ static int vaapi_device_create(AVHWDeviceContext *ctx, const char *device,
>>          return AVERROR(EINVAL);
>>      }
>>  
>> -    hwctx->display = display;
>> -
>>      vas = vaInitialize(display, &major, &minor);
>>      if (vas != VA_STATUS_SUCCESS) {
>>          av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
>>                 "connection: %d (%s).\n", vas, vaErrorStr(vas));
>>          return AVERROR(EIO);
>>      }
>> +    hwctx->display = display;
>>      av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
>>             "version %d.%d\n", major, minor);
>>  
> 
> Would that mean it doesn't free the display that was created with
> vaGetDisplay? Is that right?
> 
> In my experiments, calling vaTerminate right after vaGetDisplay works
> just fine.

Right, looking more carefully at libva that is exactly what you are meant to do, and the code there is careful to make it all work.  The segfault case I was thinking of here isn't exactly the same (and used the Intel proprietary driver, which should probably be considered dubious), so applying it was premature.

Aman, can you explain more about the case you saw this in?

- Mark
Aman Gupta Feb. 3, 2017, 10:44 p.m. UTC | #5
On Fri, Feb 3, 2017 at 12:19 PM, Mark Thompson <sw@jkqxz.net> wrote:

> On 03/02/17 05:45, wm4 wrote:
> > On Thu,  2 Feb 2017 09:29:13 -0800
> > Aman Gupta <ffmpeg@tmm1.net> wrote:
> >
> >> From: Aman Gupta <aman@tmm1.net>
> >>
> >> Program terminated with signal SIGSEGV, Segmentation fault.
> >>     opts=opts@entry=0x0, flags=flags@entry=0) at
> libavutil/hwcontext.c:494
> >> ---
> >>  libavutil/hwcontext_vaapi.c | 3 +--
> >>  1 file changed, 1 insertion(+), 2 deletions(-)
> >>
> >> diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
> >> index 6176bdc..0051acb 100644
> >> --- a/libavutil/hwcontext_vaapi.c
> >> +++ b/libavutil/hwcontext_vaapi.c
> >> @@ -961,14 +961,13 @@ static int vaapi_device_create(AVHWDeviceContext
> *ctx, const char *device,
> >>          return AVERROR(EINVAL);
> >>      }
> >>
> >> -    hwctx->display = display;
> >> -
> >>      vas = vaInitialize(display, &major, &minor);
> >>      if (vas != VA_STATUS_SUCCESS) {
> >>          av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
> >>                 "connection: %d (%s).\n", vas, vaErrorStr(vas));
> >>          return AVERROR(EIO);
> >>      }
> >> +    hwctx->display = display;
> >>      av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
> >>             "version %d.%d\n", major, minor);
> >>
> >
> > Would that mean it doesn't free the display that was created with
> > vaGetDisplay? Is that right?
> >
> > In my experiments, calling vaTerminate right after vaGetDisplay works
> > just fine.
>
> Right, looking more carefully at libva that is exactly what you are meant
> to do, and the code there is careful to make it all work.  The segfault
> case I was thinking of here isn't exactly the same (and used the Intel
> proprietary driver, which should probably be considered dubious), so
> applying it was premature.
>
> Aman, can you explain more about the case you saw this in?
>

I saw this when I was using libva master. vaInitialize() was failing in my
environment (see https://github.com/01org/libva/issues/20) and after the
failure ffmpeg crashed.

Here was the output from ffmpeg:

libva info: VA-API version 0.40.0
libva info: va_getDriverName() returns 1
libva error: va_getDriverName() failed with operation
failed,driver_name=i965
[AVHWDeviceContext @ 0x1b03d80] Failed to initialise VAAPI connection: 1
(operation failed).
Segmentation fault

And the backtrace:

  #0  0x0000000000aff8a4 in vaTerminate ()
  #1  0x0000000000ae50ce in vaapi_device_free (ctx=<optimized out>) at
libavutil/hwcontext_vaapi.c:882
  #2  0x0000000000ae1f9e in hwdevice_ctx_free (opaque=<optimized out>,
data=<optimized out>) at libavutil/hwcontext.c:66
  #3  0x0000000000ad856f in buffer_replace (src=0x0, dst=0x7fffa26ef1b8) at
libavutil/buffer.c:119
  #4  av_buffer_unref (buf=buf@entry=0x7fffa26ef1f8) at
libavutil/buffer.c:129
  #5  0x0000000000ae299f in av_hwdevice_ctx_create (pdevice_ref=0x170ac50
<hw_device_ctx>, type=type@entry=AV_HWDEVICE_TYPE_VAAPI, device=<optimized
out>,
      opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
  #6  0x0000000000400968 in vaapi_device_init (device=<optimized out>) at
ffmpeg_vaapi.c:223

Definitely possible that this is a bug in libva instead, and that failure
midway through vaInitialize() is not dealt with appropriately during
vaTerminate().

Feel free to revert the commit.

Aman


> - Mark
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
Mark Thompson Feb. 3, 2017, 11:03 p.m. UTC | #6
On 03/02/17 22:44, Aman Gupta wrote:
> On Fri, Feb 3, 2017 at 12:19 PM, Mark Thompson <sw@jkqxz.net> wrote:
> 
>> On 03/02/17 05:45, wm4 wrote:
>>> On Thu,  2 Feb 2017 09:29:13 -0800
>>> Aman Gupta <ffmpeg@tmm1.net> wrote:
>>>
>>>> From: Aman Gupta <aman@tmm1.net>
>>>>
>>>> Program terminated with signal SIGSEGV, Segmentation fault.
>>>>     opts=opts@entry=0x0, flags=flags@entry=0) at
>> libavutil/hwcontext.c:494
>>>> ---
>>>>  libavutil/hwcontext_vaapi.c | 3 +--
>>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
>>>> index 6176bdc..0051acb 100644
>>>> --- a/libavutil/hwcontext_vaapi.c
>>>> +++ b/libavutil/hwcontext_vaapi.c
>>>> @@ -961,14 +961,13 @@ static int vaapi_device_create(AVHWDeviceContext
>> *ctx, const char *device,
>>>>          return AVERROR(EINVAL);
>>>>      }
>>>>
>>>> -    hwctx->display = display;
>>>> -
>>>>      vas = vaInitialize(display, &major, &minor);
>>>>      if (vas != VA_STATUS_SUCCESS) {
>>>>          av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
>>>>                 "connection: %d (%s).\n", vas, vaErrorStr(vas));
>>>>          return AVERROR(EIO);
>>>>      }
>>>> +    hwctx->display = display;
>>>>      av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
>>>>             "version %d.%d\n", major, minor);
>>>>
>>>
>>> Would that mean it doesn't free the display that was created with
>>> vaGetDisplay? Is that right?
>>>
>>> In my experiments, calling vaTerminate right after vaGetDisplay works
>>> just fine.
>>
>> Right, looking more carefully at libva that is exactly what you are meant
>> to do, and the code there is careful to make it all work.  The segfault
>> case I was thinking of here isn't exactly the same (and used the Intel
>> proprietary driver, which should probably be considered dubious), so
>> applying it was premature.
>>
>> Aman, can you explain more about the case you saw this in?
>>
> 
> I saw this when I was using libva master. vaInitialize() was failing in my
> environment (see https://github.com/01org/libva/issues/20) and after the
> failure ffmpeg crashed.
> 
> Here was the output from ffmpeg:
> 
> libva info: VA-API version 0.40.0
> libva info: va_getDriverName() returns 1
> libva error: va_getDriverName() failed with operation
> failed,driver_name=i965
> [AVHWDeviceContext @ 0x1b03d80] Failed to initialise VAAPI connection: 1
> (operation failed).
> Segmentation fault
> 
> And the backtrace:
> 
>   #0  0x0000000000aff8a4 in vaTerminate ()
>   #1  0x0000000000ae50ce in vaapi_device_free (ctx=<optimized out>) at
> libavutil/hwcontext_vaapi.c:882
>   #2  0x0000000000ae1f9e in hwdevice_ctx_free (opaque=<optimized out>,
> data=<optimized out>) at libavutil/hwcontext.c:66
>   #3  0x0000000000ad856f in buffer_replace (src=0x0, dst=0x7fffa26ef1b8) at
> libavutil/buffer.c:119
>   #4  av_buffer_unref (buf=buf@entry=0x7fffa26ef1f8) at
> libavutil/buffer.c:129
>   #5  0x0000000000ae299f in av_hwdevice_ctx_create (pdevice_ref=0x170ac50
> <hw_device_ctx>, type=type@entry=AV_HWDEVICE_TYPE_VAAPI, device=<optimized
> out>,
>       opts=opts@entry=0x0, flags=flags@entry=0) at libavutil/hwcontext.c:494
>   #6  0x0000000000400968 in vaapi_device_init (device=<optimized out>) at
> ffmpeg_vaapi.c:223
> 
> Definitely possible that this is a bug in libva instead, and that failure
> midway through vaInitialize() is not dealt with appropriately during
> vaTerminate().
> 
> Feel free to revert the commit.

Can you build libva with debug enabled and clarify exactly how and where it's failing there?  From your description on github I'm inclined to think it is some bad interaction in libva with running as root, but it would be good to be sure.  (And we should revert the change here.)

Thanks,

- Mark
diff mbox

Patch

diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
index 6176bdc..0051acb 100644
--- a/libavutil/hwcontext_vaapi.c
+++ b/libavutil/hwcontext_vaapi.c
@@ -961,14 +961,13 @@  static int vaapi_device_create(AVHWDeviceContext *ctx, const char *device,
         return AVERROR(EINVAL);
     }
 
-    hwctx->display = display;
-
     vas = vaInitialize(display, &major, &minor);
     if (vas != VA_STATUS_SUCCESS) {
         av_log(ctx, AV_LOG_ERROR, "Failed to initialise VAAPI "
                "connection: %d (%s).\n", vas, vaErrorStr(vas));
         return AVERROR(EIO);
     }
+    hwctx->display = display;
     av_log(ctx, AV_LOG_VERBOSE, "Initialised VAAPI connection: "
            "version %d.%d\n", major, minor);