| Message ID | 20200520142347.29060-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm: Restore the NULL check for drm_gem_object_put() | expand |
On Wed, 20 May 2020 at 15:24, Chris Wilson <chris@chris-wilson.co.uk> wrote: > > Some users want to pass NULL to drm_gem_object_put(), but those using > __drm_gem_object_put() did not. Compromise, have both and let the > compiler sort it out. > > drm_gem_fb_destroy() calls drm_gem_object_put() with NULL obj causing: > [ 11.584209] BUG: kernel NULL pointer dereference, address: 0000000000000000 > [ 11.584213] #PF: supervisor write access in kernel mode > [ 11.584215] #PF: error_code(0x0002) - not-present page > [ 11.584216] PGD 0 P4D 0 > [ 11.584220] Oops: 0002 [#1] SMP NOPTI > [ 11.584223] CPU: 7 PID: 1571 Comm: gnome-shell Tainted: G E 5.7.0-rc1-1-default+ #27 > [ 11.584225] Hardware name: Micro-Star International Co., Ltd. MS-7A31/X370 XPOWER GAMING TITANIUM (MS-7A31), BIOS 1.MR 12/03/2019 > [ 11.584237] RIP: 0010:drm_gem_fb_destroy+0x28/0x70 [drm_kms_helper] > <snip> > [ 11.584256] Call Trace: > [ 11.584279] drm_mode_rmfb+0x189/0x1c0 [drm] > [ 11.584299] ? drm_mode_rmfb+0x1c0/0x1c0 [drm] > [ 11.584314] drm_ioctl_kernel+0xaa/0xf0 [drm] > [ 11.584329] drm_ioctl+0x1ff/0x3b0 [drm] > [ 11.584347] ? drm_mode_rmfb+0x1c0/0x1c0 [drm] > [ 11.584421] amdgpu_drm_ioctl+0x49/0x80 [amdgpu] > [ 11.584427] ksys_ioctl+0x87/0xc0 > [ 11.584430] __x64_sys_ioctl+0x16/0x20 > [ 11.584434] do_syscall_64+0x5f/0x240 > [ 11.584438] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > [ 11.584440] RIP: 0033:0x7f0ef80f7227 > > Reported-by: Nirmoy Das <nirmoy.das@amd.com> > Fixes: b5d250744ccc ("drm/gem: fold drm_gem_object_put_unlocked and __drm_gem_object_put()") > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Nirmoy Das <nirmoy.das@amd.com> > Cc: Emil Velikov <emil.velikov@collabora.com> > Cc: Christian König <christian.koenig@amd.com>. > Acked-by: Nirmoy Das <nirmoy.das@amd.com> Reviewed-by: Emil Velikov <emil.velikov@collabora.com> I'm half way through checking the callers and I've noticed a handful of bugs. Will send the series in due time, although your patch is a perfect intermediate solution. Thank you Emil
Quoting Emil Velikov (2020-05-20 15:25:05) > Reviewed-by: Emil Velikov <emil.velikov@collabora.com> > > I'm half way through checking the callers and I've noticed a handful of bugs. > Will send the series in due time, although your patch is a perfect > intermediate solution. Pushed the compromise patch. That should keep us all happy within our own little bubbles for the moment. Have fun! -Chris
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h index aba7517c2837..2faa481cc18f 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_object.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h @@ -105,7 +105,7 @@ __attribute__((nonnull)) static inline void i915_gem_object_put(struct drm_i915_gem_object *obj) { - drm_gem_object_put(&obj->base); + __drm_gem_object_put(&obj->base); } #define assert_object_held(obj) dma_resv_assert_held((obj)->base.resv) diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 52173abdf500..2410ff0a8e86 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -363,6 +363,13 @@ static inline void drm_gem_object_get(struct drm_gem_object *obj) kref_get(&obj->refcount); } +__attribute__((nonnull)) +static inline void +__drm_gem_object_put(struct drm_gem_object *obj) +{ + kref_put(&obj->refcount, drm_gem_object_free); +} + /** * drm_gem_object_put - drop a GEM buffer object reference * @obj: GEM buffer object @@ -372,7 +379,8 @@ static inline void drm_gem_object_get(struct drm_gem_object *obj) static inline void drm_gem_object_put(struct drm_gem_object *obj) { - kref_put(&obj->refcount, drm_gem_object_free); + if (obj) + __drm_gem_object_put(obj); } void drm_gem_object_put_locked(struct drm_gem_object *obj);
Some users want to pass NULL to drm_gem_object_put(), but those using __drm_gem_object_put() did not. Compromise, have both and let the compiler sort it out. drm_gem_fb_destroy() calls drm_gem_object_put() with NULL obj causing: [ 11.584209] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 11.584213] #PF: supervisor write access in kernel mode [ 11.584215] #PF: error_code(0x0002) - not-present page [ 11.584216] PGD 0 P4D 0 [ 11.584220] Oops: 0002 [#1] SMP NOPTI [ 11.584223] CPU: 7 PID: 1571 Comm: gnome-shell Tainted: G E 5.7.0-rc1-1-default+ #27 [ 11.584225] Hardware name: Micro-Star International Co., Ltd. MS-7A31/X370 XPOWER GAMING TITANIUM (MS-7A31), BIOS 1.MR 12/03/2019 [ 11.584237] RIP: 0010:drm_gem_fb_destroy+0x28/0x70 [drm_kms_helper] <snip> [ 11.584256] Call Trace: [ 11.584279] drm_mode_rmfb+0x189/0x1c0 [drm] [ 11.584299] ? drm_mode_rmfb+0x1c0/0x1c0 [drm] [ 11.584314] drm_ioctl_kernel+0xaa/0xf0 [drm] [ 11.584329] drm_ioctl+0x1ff/0x3b0 [drm] [ 11.584347] ? drm_mode_rmfb+0x1c0/0x1c0 [drm] [ 11.584421] amdgpu_drm_ioctl+0x49/0x80 [amdgpu] [ 11.584427] ksys_ioctl+0x87/0xc0 [ 11.584430] __x64_sys_ioctl+0x16/0x20 [ 11.584434] do_syscall_64+0x5f/0x240 [ 11.584438] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 11.584440] RIP: 0033:0x7f0ef80f7227 Reported-by: Nirmoy Das <nirmoy.das@amd.com> Fixes: b5d250744ccc ("drm/gem: fold drm_gem_object_put_unlocked and __drm_gem_object_put()") Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Nirmoy Das <nirmoy.das@amd.com> Cc: Emil Velikov <emil.velikov@collabora.com> Cc: Christian König <christian.koenig@amd.com>. Acked-by: Nirmoy Das <nirmoy.das@amd.com> --- drivers/gpu/drm/i915/gem/i915_gem_object.h | 2 +- include/drm/drm_gem.h | 10 +++++++++- 2 files changed, 10 insertions(+), 2 deletions(-)