Messages in this thread | | | Date | Tue, 30 Nov 2021 14:58:18 +0000 | Subject | Re: [Intel-gfx] [PATCH] drm/i915/gem: Fix a NULL pointer dereference in igt_request_rewind() | From | Tvrtko Ursulin <> |
| |
On 30/11/2021 14:15, Zhou Qingyang wrote: > In igt_request_rewind(), mock_context(i915, "A") is assigned to ctx[0] > and used in i915_gem_context_get_engine(). There is a dereference > of ctx[0] in i915_gem_context_get_engine(), which could lead to a NULL > pointer dereference on failure of mock_context(i915, "A") . > > So as mock_context(i915, "B"). > > Although this bug is not serious for it belongs to testing code, it is > better to be fixed to avoid unexpected failure in testing. > > Fix this bugs by adding checks about ctx[0] and ctx[1]. > > This bug was found by a static analyzer. The analysis employs > differential checking to identify inconsistent security operations > (e.g., checks or kfrees) between two code paths and confirms that the > inconsistent operations are not recovered in the current function or > the callers, so they constitute bugs. > > Note that, as a bug found by static analysis, it can be a false > positive or hard to trigger. Multiple researchers have cross-reviewed > the bug. > > Builds with CONFIG_DRM_I915_SELFTEST=y show no new warnings, > and our static analyzer no longer warns about this code. > > Fixes: ca883c304f54 ("drm/i915/selftests: Pass intel_context to mock_request")
I think it is this one instead:
591c0fb85d1c ("drm/i915: Exercise request cancellation using a mock selftest")
Fix looks correct so:
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Thanks for the patch!
Regards,
Tvrtko
P.S. Although Fixes: is probably a bit over the top since it is selftests only so I'll probably drop it while applying.
> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> > --- > drivers/gpu/drm/i915/selftests/i915_request.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/gpu/drm/i915/selftests/i915_request.c b/drivers/gpu/drm/i915/selftests/i915_request.c > index d67710d10615..d6fc7b892793 100644 > --- a/drivers/gpu/drm/i915/selftests/i915_request.c > +++ b/drivers/gpu/drm/i915/selftests/i915_request.c > @@ -209,6 +209,10 @@ static int igt_request_rewind(void *arg) > int err = -EINVAL; > > ctx[0] = mock_context(i915, "A"); > + if (!ctx[0]) { > + err = -ENOMEM; > + goto err_ctx_0; > + } > > ce = i915_gem_context_get_engine(ctx[0], RCS0); > GEM_BUG_ON(IS_ERR(ce)); > @@ -223,6 +227,10 @@ static int igt_request_rewind(void *arg) > i915_request_add(request); > > ctx[1] = mock_context(i915, "B"); > + if (!ctx[1]) { > + err = -ENOMEM; > + goto err_ctx_1; > + } > > ce = i915_gem_context_get_engine(ctx[1], RCS0); > GEM_BUG_ON(IS_ERR(ce)); > @@ -261,9 +269,11 @@ static int igt_request_rewind(void *arg) > i915_request_put(vip); > err_context_1: > mock_context_close(ctx[1]); > +err_ctx_1: > i915_request_put(request); > err_context_0: > mock_context_close(ctx[0]); > +err_ctx_0: > mock_device_flush(i915); > return err; > } >
| |