On Mon, Dec 02, 2013 at 06:32:51PM +0200, Mika Kuoppala wrote:
> Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes:
>
> > On Mon, Dec 02, 2013 at 04:47:46PM +0200, Mika Kuoppala wrote:
> >> Fork and create another filedesc to wait access to already
> >> hung GPU and then kill it. This triggers use after free of the
> >> request->batch_obj.
> >>
> >> Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx>
> >> ---
> >> +static int __test_open_any(void)
> >> +{
> >> + char *name;
> >> + int ret, fd;
> >> +
> >> + ret = asprintf(&name, "/dev/dri/card%d", drm_get_card());
> >> + if (ret == -1)
> >> + return -1;
> >> +
> >> + fd = open(name, O_RDWR);
> >> + free(name);
> >> +
> >> + return fd;
> >> +}
> >> +
> >> +static void test_close_pending_fork(void)
> >> +{
> >> + int pid;
> >> + int fd, fd2, h;
> >> +
> >> + fd = drm_open_any();
> >> + igt_assert(fd >= 0);
> >
> > [snip]
> >
> >> + close(fd);
> >> +
> >> + fd = drm_open_any();
> >
> > This breaks the testsuite since drm_open_any() will now return the
> > closed fd. Hence your __test_open_any() above.
> >
> > However this does not justify kernel doing anything other than terminating
> > your process with extreme prejudice.
>
> I discussed this with Chris in IRC. There seems to be no problem
> as drm_open_any doesn't cache file descriptors.
>
> The reason i use __test_open_any is that I needed a way to bypass
> testsuites exit handling.
I guess a quick comment to explain that in the code would help. Can you
please update the patch?
-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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