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
Signed-off-by: Nirmoy Das nirmoy.das@amd.com --- include/drm/drm_gem.h | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index 52173abdf500..a13510346a9b 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -372,6 +372,9 @@ static inline void drm_gem_object_get(struct drm_gem_object *obj) static inline void drm_gem_object_put(struct drm_gem_object *obj) { + if (!obj) + return; + kref_put(&obj->refcount, drm_gem_object_free); }