The function drm_gem_shmem_vmap can returns error pointers as well, which could cause following kernel crash:
BUG: unable to handle page fault for address: fffffffffffffffc PGD 1426a12067 P4D 1426a12067 PUD 1426a14067 PMD 0 Oops: 0000 [#1] SMP NOPTI CPU: 12 PID: 3598532 Comm: stress-ng Kdump: loaded Not tainted 5.10.50.x86_64 #1 ... RIP: 0010:memcpy_toio+0x23/0x50 Code: 00 00 00 00 0f 1f 00 0f 1f 44 00 00 48 85 d2 74 28 40 f6 c7 01 75 2b 48 83 fa 01 76 06 40 f6 c7 02 75 17 48 89 d1 48 c1 e9 02 <f3> a5 f6 c2 02 74 02 66 a5 f6 c2 01 74 01 a4 c3 66 a5 48 83 ea 02 RSP: 0018:ffffafbf8a203c68 EFLAGS: 00010216 RAX: 0000000000000000 RBX: fffffffffffffffc RCX: 0000000000000200 RDX: 0000000000000800 RSI: fffffffffffffffc RDI: ffffafbf82000000 RBP: ffffafbf82000000 R08: 0000000000000002 R09: 0000000000000000 R10: 00000000000002b5 R11: 0000000000000000 R12: 0000000000000800 R13: ffff8a6801099300 R14: 0000000000000001 R15: 0000000000000300 FS: 00007f4a6bc5f740(0000) GS:ffff8a8641900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffffffffffffc CR3: 00000016d3874001 CR4: 00000000003606e0 Call Trace: drm_fb_memcpy_dstclip+0x5e/0x80 [drm_kms_helper] cirrus_fb_blit_rect.isra.0+0xb7/0xe0 [cirrus] cirrus_pipe_update+0x9f/0xa8 [cirrus] drm_atomic_helper_commit_planes+0xb8/0x220 [drm_kms_helper] drm_atomic_helper_commit_tail+0x42/0x80 [drm_kms_helper] commit_tail+0xce/0x130 [drm_kms_helper] drm_atomic_helper_commit+0x113/0x140 [drm_kms_helper] drm_client_modeset_commit_atomic+0x1c4/0x200 [drm] drm_client_modeset_commit_locked+0x53/0x80 [drm] drm_client_modeset_commit+0x24/0x40 [drm] drm_fbdev_client_restore+0x48/0x85 [drm_kms_helper] drm_client_dev_restore+0x64/0xb0 [drm] drm_release+0xf2/0x110 [drm] __fput+0x96/0x240 task_work_run+0x5c/0x90 exit_to_user_mode_loop+0xce/0xd0 exit_to_user_mode_prepare+0x6a/0x70 syscall_exit_to_user_mode+0x12/0x40 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f4a6bd82c2b
Fixes: ab3e023b1b4c9 ("drm/cirrus: rewrite and modernize driver.")
Signed-off-by: Shile Zhang shile.zhang@linux.alibaba.com --- v2: rebase to latest stable linux-5.10.y branch. v1: https://lore.kernel.org/lkml/550e9439-adf6-3df8-41a0-9a7ee5447907@linux.alib... --- drivers/gpu/drm/tiny/cirrus.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c index 744a8e337e41e..d64f6bb767eeb 100644 --- a/drivers/gpu/drm/tiny/cirrus.c +++ b/drivers/gpu/drm/tiny/cirrus.c @@ -323,7 +323,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
ret = -ENOMEM; vmap = drm_gem_shmem_vmap(fb->obj[0]); - if (!vmap) + if (IS_ERR_OR_NULL(vmap)) goto out_dev_exit;
if (cirrus->cpp == fb->format->cpp[0])