| Message ID | 1491380967-28570-9-git-send-email-jeffy.chen@rock-chips.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: > After unbinding drm, the userspace may still has a chance to access > gem buf. > > Add a sanity check for a NULL dev_private to prevent that from > happening. I still don't understand how this is happening. You're saying that these hooks can be called after rockchip_drm_unbind() has finished? Sean > > Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> > --- > > Changes in v3: > Address Daniel Vetter <daniel@ffwll.ch>'s comments. > Update commit message. > > Changes in v2: None > > drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > index df9e570..205a3dc 100644 > --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, > struct drm_device *drm = obj->dev; > struct rockchip_drm_private *private = drm->dev_private; > > + if (!private) > + return -ENODEV; > + > if (private->domain) > return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); > else > @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) > > static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) > { > + struct drm_device *drm = rk_obj->base.dev; > + > + if (!drm->dev_private) > + return; > + > if (rk_obj->pages) > rockchip_gem_free_iommu(rk_obj); > else > -- > 2.1.4 >
Hi Sean, On 04/06/2017 12:28 AM, Sean Paul wrote: > On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: >> After unbinding drm, the userspace may still has a chance to access >> gem buf. >> >> Add a sanity check for a NULL dev_private to prevent that from >> happening. > > I still don't understand how this is happening. You're saying that these hooks > can be called after rockchip_drm_unbind() has finished? > yes, tested on chromebook rk3399 kevin with kernel 4.4, if trigger unbind without killing display service(ui or frecon): [ 31.276889] [<ffffffc0002089e4>] dump_backtrace+0x0/0x164 [ 31.282288] [<ffffffc000208b6c>] show_stack+0x24/0x30 [ 31.287338] [<ffffffc0004be028>] dump_stack+0x98/0xb8 [ 31.292389] [<ffffffc0005c0b8c>] rockchip_gem_create_object+0x6c/0x2ec [ 31.298910] [<ffffffc0005c0fa0>] rockchip_gem_create_with_handle+0x38/0x10c [ 31.305868] [<ffffffc0005c12b8>] rockchip_gem_create_ioctl+0x38/0x50 [ 31.312221] [<ffffffc000598844>] drm_ioctl+0x2bc/0x438 [ 31.317359] [<ffffffc0005b5ee0>] drm_compat_ioctl+0x3c/0x70 [ 31.322935] [<ffffffc0003a6960>] compat_SyS_ioctl+0x134/0x1048 [ 31.328766] [<ffffffc000203e90>] __sys_trace_return+0x0/0x4 > Sean > >> >> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> >> --- >> >> Changes in v3: >> Address Daniel Vetter <daniel@ffwll.ch>'s comments. >> Update commit message. >> >> Changes in v2: None >> >> drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >> index df9e570..205a3dc 100644 >> --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >> @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, >> struct drm_device *drm = obj->dev; >> struct rockchip_drm_private *private = drm->dev_private; >> >> + if (!private) >> + return -ENODEV; >> + >> if (private->domain) >> return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); >> else >> @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) >> >> static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) >> { >> + struct drm_device *drm = rk_obj->base.dev; >> + >> + if (!drm->dev_private) >> + return; >> + >> if (rk_obj->pages) >> rockchip_gem_free_iommu(rk_obj); >> else >> -- >> 2.1.4 >> >
On Wed, Apr 05, 2017 at 12:28:40PM -0400, Sean Paul wrote: > On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: > > After unbinding drm, the userspace may still has a chance to access > > gem buf. > > > > Add a sanity check for a NULL dev_private to prevent that from > > happening. > > I still don't understand how this is happening. You're saying that these hooks > can be called after rockchip_drm_unbind() has finished? Yeah this is supposed to be impossible. If it isn't, we need to debug and fix this properly. This smells like pretty bad duct-tape ... -Daniel > > Sean > > > > > Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> > > --- > > > > Changes in v3: > > Address Daniel Vetter <daniel@ffwll.ch>'s comments. > > Update commit message. > > > > Changes in v2: None > > > > drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > > index df9e570..205a3dc 100644 > > --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > > @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, > > struct drm_device *drm = obj->dev; > > struct rockchip_drm_private *private = drm->dev_private; > > > > + if (!private) > > + return -ENODEV; > > + > > if (private->domain) > > return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); > > else > > @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) > > > > static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) > > { > > + struct drm_device *drm = rk_obj->base.dev; > > + > > + if (!drm->dev_private) > > + return; > > + > > if (rk_obj->pages) > > rockchip_gem_free_iommu(rk_obj); > > else > > -- > > 2.1.4 > > > > -- > Sean Paul, Software Engineer, Google / Chromium OS > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel
Hi Daniel, On 04/06/2017 04:26 PM, Daniel Vetter wrote: > On Wed, Apr 05, 2017 at 12:28:40PM -0400, Sean Paul wrote: >> On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: >>> After unbinding drm, the userspace may still has a chance to access >>> gem buf. >>> >>> Add a sanity check for a NULL dev_private to prevent that from >>> happening. >> >> I still don't understand how this is happening. You're saying that these hooks >> can be called after rockchip_drm_unbind() has finished? > > Yeah this is supposed to be impossible. If it isn't, we need to debug and > fix this properly. This smells like pretty bad duct-tape ... it looks like after unbind, the user space may still own drm dev fd, and could be able to call ioctl: lrwx------. 1 chronos chronos 64 Mar 15 12:53 28 -> /dev/dri/card1 (deleted) and the drm_unplug_dev may help it, maybe we should call it in unbind? or just break drm_ioctl when drm_dev not registered? > -Daniel > >> >> Sean >> >>> >>> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> >>> --- >>> >>> Changes in v3: >>> Address Daniel Vetter <daniel@ffwll.ch>'s comments. >>> Update commit message. >>> >>> Changes in v2: None >>> >>> drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ >>> 1 file changed, 8 insertions(+) >>> >>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>> index df9e570..205a3dc 100644 >>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>> @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, >>> struct drm_device *drm = obj->dev; >>> struct rockchip_drm_private *private = drm->dev_private; >>> >>> + if (!private) >>> + return -ENODEV; >>> + >>> if (private->domain) >>> return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); >>> else >>> @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) >>> >>> static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) >>> { >>> + struct drm_device *drm = rk_obj->base.dev; >>> + >>> + if (!drm->dev_private) >>> + return; >>> + >>> if (rk_obj->pages) >>> rockchip_gem_free_iommu(rk_obj); >>> else >>> -- >>> 2.1.4 >>> >> >> -- >> Sean Paul, Software Engineer, Google / Chromium OS >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel >
On Thu, Apr 06, 2017 at 10:47:59AM +0800, jeffy wrote: > Hi Sean, > > On 04/06/2017 12:28 AM, Sean Paul wrote: > > On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: > > > After unbinding drm, the userspace may still has a chance to access > > > gem buf. > > > > > > Add a sanity check for a NULL dev_private to prevent that from > > > happening. > > > > I still don't understand how this is happening. You're saying that these hooks > > can be called after rockchip_drm_unbind() has finished? > > > yes, tested on chromebook rk3399 kevin with kernel 4.4, if trigger unbind > without killing display service(ui or frecon): > > [ 31.276889] [<ffffffc0002089e4>] dump_backtrace+0x0/0x164 > [ 31.282288] [<ffffffc000208b6c>] show_stack+0x24/0x30 > [ 31.287338] [<ffffffc0004be028>] dump_stack+0x98/0xb8 > [ 31.292389] [<ffffffc0005c0b8c>] rockchip_gem_create_object+0x6c/0x2ec > [ 31.298910] [<ffffffc0005c0fa0>] > rockchip_gem_create_with_handle+0x38/0x10c > [ 31.305868] [<ffffffc0005c12b8>] rockchip_gem_create_ioctl+0x38/0x50 > [ 31.312221] [<ffffffc000598844>] drm_ioctl+0x2bc/0x438 > [ 31.317359] [<ffffffc0005b5ee0>] drm_compat_ioctl+0x3c/0x70 > [ 31.322935] [<ffffffc0003a6960>] compat_SyS_ioctl+0x134/0x1048 > [ 31.328766] [<ffffffc000203e90>] __sys_trace_return+0x0/0x4 Hi Jeffy, I'm not suggesting this doesn't happen, I believe you :-). I'd really like to know *why* it happens. Are you sure that unbind has completely finished before this trace occurs? Perhaps this is results from a race between unbind and gem allocate? Sean > > > Sean > > > > > > > > Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> > > > --- > > > > > > Changes in v3: > > > Address Daniel Vetter <daniel@ffwll.ch>'s comments. > > > Update commit message. > > > > > > Changes in v2: None > > > > > > drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > > > index df9e570..205a3dc 100644 > > > --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > > > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c > > > @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, > > > struct drm_device *drm = obj->dev; > > > struct rockchip_drm_private *private = drm->dev_private; > > > > > > + if (!private) > > > + return -ENODEV; > > > + > > > if (private->domain) > > > return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); > > > else > > > @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) > > > > > > static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) > > > { > > > + struct drm_device *drm = rk_obj->base.dev; > > > + > > > + if (!drm->dev_private) > > > + return; > > > + > > > if (rk_obj->pages) > > > rockchip_gem_free_iommu(rk_obj); > > > else > > > -- > > > 2.1.4 > > > > > >
Hi Sean, On 04/06/2017 08:26 PM, Sean Paul wrote: > On Thu, Apr 06, 2017 at 10:47:59AM +0800, jeffy wrote: >> Hi Sean, >> >> On 04/06/2017 12:28 AM, Sean Paul wrote: >>> On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: >>>> After unbinding drm, the userspace may still has a chance to access >>>> gem buf. >>>> >>>> Add a sanity check for a NULL dev_private to prevent that from >>>> happening. >>> >>> I still don't understand how this is happening. You're saying that these hooks >>> can be called after rockchip_drm_unbind() has finished? >>> >> yes, tested on chromebook rk3399 kevin with kernel 4.4, if trigger unbind >> without killing display service(ui or frecon): >> >> [ 31.276889] [<ffffffc0002089e4>] dump_backtrace+0x0/0x164 >> [ 31.282288] [<ffffffc000208b6c>] show_stack+0x24/0x30 >> [ 31.287338] [<ffffffc0004be028>] dump_stack+0x98/0xb8 >> [ 31.292389] [<ffffffc0005c0b8c>] rockchip_gem_create_object+0x6c/0x2ec >> [ 31.298910] [<ffffffc0005c0fa0>] >> rockchip_gem_create_with_handle+0x38/0x10c >> [ 31.305868] [<ffffffc0005c12b8>] rockchip_gem_create_ioctl+0x38/0x50 >> [ 31.312221] [<ffffffc000598844>] drm_ioctl+0x2bc/0x438 >> [ 31.317359] [<ffffffc0005b5ee0>] drm_compat_ioctl+0x3c/0x70 >> [ 31.322935] [<ffffffc0003a6960>] compat_SyS_ioctl+0x134/0x1048 >> [ 31.328766] [<ffffffc000203e90>] __sys_trace_return+0x0/0x4 > > Hi Jeffy, > I'm not suggesting this doesn't happen, I believe you :-). I'd really like to > know *why* it happens. > > Are you sure that unbind has completely finished before this trace occurs? > Perhaps this is results from a race between unbind and gem allocate? yes, that unbind is finished. and it looks like the display server still holds drm dev fd(even it been deleted after unbind). sometimes i can see it trigger ioctl even seconds later. i'll send a patch to break drm_ioctl after unbind. > > Sean > >> >>> Sean >>> >>>> >>>> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> >>>> --- >>>> >>>> Changes in v3: >>>> Address Daniel Vetter <daniel@ffwll.ch>'s comments. >>>> Update commit message. >>>> >>>> Changes in v2: None >>>> >>>> drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ >>>> 1 file changed, 8 insertions(+) >>>> >>>> diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>>> index df9e570..205a3dc 100644 >>>> --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>>> +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c >>>> @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, >>>> struct drm_device *drm = obj->dev; >>>> struct rockchip_drm_private *private = drm->dev_private; >>>> >>>> + if (!private) >>>> + return -ENODEV; >>>> + >>>> if (private->domain) >>>> return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); >>>> else >>>> @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) >>>> >>>> static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) >>>> { >>>> + struct drm_device *drm = rk_obj->base.dev; >>>> + >>>> + if (!drm->dev_private) >>>> + return; >>>> + >>>> if (rk_obj->pages) >>>> rockchip_gem_free_iommu(rk_obj); >>>> else >>>> -- >>>> 2.1.4 >>>> >>> >> >
On Thu, Apr 6, 2017 at 1:09 PM, jeffy <jeffy.chen@rock-chips.com> wrote: > > On 04/06/2017 04:26 PM, Daniel Vetter wrote: >> >> On Wed, Apr 05, 2017 at 12:28:40PM -0400, Sean Paul wrote: >>> >>> On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: >>>> >>>> After unbinding drm, the userspace may still has a chance to access >>>> gem buf. >>>> >>>> Add a sanity check for a NULL dev_private to prevent that from >>>> happening. >>> >>> >>> I still don't understand how this is happening. You're saying that these >>> hooks >>> can be called after rockchip_drm_unbind() has finished? >> >> >> Yeah this is supposed to be impossible. If it isn't, we need to debug and >> fix this properly. This smells like pretty bad duct-tape ... > > > it looks like after unbind, the user space may still own drm dev fd, and > could be able to call ioctl: > lrwx------. 1 chronos chronos 64 Mar 15 12:53 28 -> /dev/dri/card1 (deleted) > > and the drm_unplug_dev may help it, maybe we should call it in unbind? or > just break drm_ioctl when drm_dev not registered? Yes, by default unbind while userspace is running is totally broken in drm. drm_unplug_dev would be the fix, but it's only used by udl and not many use that. You might need to fix infrastructure up a bit. For normal module unload the module reference will prevent unloading. So why exactly do you care about the unbind use-case? -Daniel
Hi Daniel, On 04/07/2017 02:30 PM, Daniel Vetter wrote: > On Thu, Apr 6, 2017 at 1:09 PM, jeffy <jeffy.chen@rock-chips.com> wrote: >> >> On 04/06/2017 04:26 PM, Daniel Vetter wrote: >>> >>> On Wed, Apr 05, 2017 at 12:28:40PM -0400, Sean Paul wrote: >>>> >>>> On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: >>>>> >>>>> After unbinding drm, the userspace may still has a chance to access >>>>> gem buf. >>>>> >>>>> Add a sanity check for a NULL dev_private to prevent that from >>>>> happening. >>>> >>>> >>>> I still don't understand how this is happening. You're saying that these >>>> hooks >>>> can be called after rockchip_drm_unbind() has finished? >>> >>> >>> Yeah this is supposed to be impossible. If it isn't, we need to debug and >>> fix this properly. This smells like pretty bad duct-tape ... >> >> >> it looks like after unbind, the user space may still own drm dev fd, and >> could be able to call ioctl: >> lrwx------. 1 chronos chronos 64 Mar 15 12:53 28 -> /dev/dri/card1 (deleted) >> >> and the drm_unplug_dev may help it, maybe we should call it in unbind? or >> just break drm_ioctl when drm_dev not registered? > > Yes, by default unbind while userspace is running is totally broken in > drm. drm_unplug_dev would be the fix, but it's only used by udl and > not many use that. You might need to fix infrastructure up a bit. please check this patch: 9667071 New [v5,12/12] drm/drm_ioctl.c: Break ioctl when drm device not registered > > For normal module unload the module reference will prevent unloading. > So why exactly do you care about the unbind use-case? sometimes we use unbind/bind for testing ;) > -Daniel >
On Fri, Apr 07, 2017 at 02:44:05PM +0800, jeffy wrote: > Hi Daniel, > > On 04/07/2017 02:30 PM, Daniel Vetter wrote: > > On Thu, Apr 6, 2017 at 1:09 PM, jeffy <jeffy.chen@rock-chips.com> wrote: > > > > > > On 04/06/2017 04:26 PM, Daniel Vetter wrote: > > > > > > > > On Wed, Apr 05, 2017 at 12:28:40PM -0400, Sean Paul wrote: > > > > > > > > > > On Wed, Apr 05, 2017 at 04:29:26PM +0800, Jeffy Chen wrote: > > > > > > > > > > > > After unbinding drm, the userspace may still has a chance to access > > > > > > gem buf. > > > > > > > > > > > > Add a sanity check for a NULL dev_private to prevent that from > > > > > > happening. > > > > > > > > > > > > > > > I still don't understand how this is happening. You're saying that these > > > > > hooks > > > > > can be called after rockchip_drm_unbind() has finished? > > > > > > > > > > > > Yeah this is supposed to be impossible. If it isn't, we need to debug and > > > > fix this properly. This smells like pretty bad duct-tape ... > > > > > > > > > it looks like after unbind, the user space may still own drm dev fd, and > > > could be able to call ioctl: > > > lrwx------. 1 chronos chronos 64 Mar 15 12:53 28 -> /dev/dri/card1 (deleted) > > > > > > and the drm_unplug_dev may help it, maybe we should call it in unbind? or > > > just break drm_ioctl when drm_dev not registered? > > > > Yes, by default unbind while userspace is running is totally broken in > > drm. drm_unplug_dev would be the fix, but it's only used by udl and > > not many use that. You might need to fix infrastructure up a bit. > please check this patch: > 9667071 New [v5,12/12] drm/drm_ioctl.c: Break ioctl when drm device > not registered > > > > For normal module unload the module reference will prevent unloading. > > So why exactly do you care about the unbind use-case? > sometimes we use unbind/bind for testing ;) Then make sure you stop your userspace first. Fixing unbind to be completely race-free requires a bit of work in the drm core. -Daniel
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c index df9e570..205a3dc 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c @@ -184,6 +184,9 @@ static int rockchip_gem_alloc_buf(struct rockchip_gem_object *rk_obj, struct drm_device *drm = obj->dev; struct rockchip_drm_private *private = drm->dev_private; + if (!private) + return -ENODEV; + if (private->domain) return rockchip_gem_alloc_iommu(rk_obj, alloc_kmap); else @@ -208,6 +211,11 @@ static void rockchip_gem_free_dma(struct rockchip_gem_object *rk_obj) static void rockchip_gem_free_buf(struct rockchip_gem_object *rk_obj) { + struct drm_device *drm = rk_obj->base.dev; + + if (!drm->dev_private) + return; + if (rk_obj->pages) rockchip_gem_free_iommu(rk_obj); else
After unbinding drm, the userspace may still has a chance to access gem buf. Add a sanity check for a NULL dev_private to prevent that from happening. Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com> --- Changes in v3: Address Daniel Vetter <daniel@ffwll.ch>'s comments. Update commit message. Changes in v2: None drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 8 ++++++++ 1 file changed, 8 insertions(+)