From: Shang XiaoJing shangxiaojing@huawei.com
[ Upstream commit 4979524f5a2a8210e87fde2f642b0dc060860821 ]
drm_vblank_init() call drmm_add_action_or_reset() with drm_vblank_init_release() as action. If __drmm_add_action() failed, will directly call drm_vblank_init_release() with the vblank whose worker is NULL. As the resule, a null-ptr-deref will happen in kthread_destroy_worker(). Add the NULL check before calling drm_vblank_destroy_worker().
BUG: null-ptr-deref KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f] CPU: 5 PID: 961 Comm: modprobe Not tainted 6.0.0-11331-gd465bff130bf-dirty RIP: 0010:kthread_destroy_worker+0x25/0xb0 Call Trace: <TASK> drm_vblank_init_release+0x124/0x220 [drm] ? drm_crtc_vblank_restore+0x8b0/0x8b0 [drm] __drmm_add_action_or_reset+0x41/0x50 [drm] drm_vblank_init+0x282/0x310 [drm] vkms_init+0x35f/0x1000 [vkms] ? 0xffffffffc4508000 ? lock_is_held_type+0xd7/0x130 ? __kmem_cache_alloc_node+0x1c2/0x2b0 ? lock_is_held_type+0xd7/0x130 ? 0xffffffffc4508000 do_one_initcall+0xd0/0x4f0 ... do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0
Fixes: 5e6c2b4f9161 ("drm/vblank: Add vblank works") Signed-off-by: Shang XiaoJing shangxiaojing@huawei.com Reviewed-by: Lyude Paul lyude@redhat.com Signed-off-by: Lyude Paul lyude@redhat.com Link: https://patchwork.freedesktop.org/patch/msgid/20221101070716.9189-3-shangxia... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/drm_internal.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index 7bb98e6a446d..5ea5e260118c 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -104,7 +104,8 @@ static inline void drm_vblank_flush_worker(struct drm_vblank_crtc *vblank)
static inline void drm_vblank_destroy_worker(struct drm_vblank_crtc *vblank) { - kthread_destroy_worker(vblank->worker); + if (vblank->worker) + kthread_destroy_worker(vblank->worker); }
int drm_vblank_worker_init(struct drm_vblank_crtc *vblank);