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* [PATCH 1/1] drm: check for NULL pointer in drm_gem_object_put
@ 2020-05-20 12:14 Nirmoy Das
  2020-05-20 12:19 ` Christian König
  0 siblings, 1 reply; 12+ messages in thread
From: Nirmoy Das @ 2020-05-20 12:14 UTC (permalink / raw)
  To: dri-devel; +Cc: Nirmoy Das, christian.koenig, nirmoy.aiemd

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);
 }
 
-- 
2.26.2

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^ permalink raw reply related	[flat|nested] 12+ messages in thread

end of thread, other threads:[~2020-05-22  6:56 UTC | newest]

Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-05-20 12:14 [PATCH 1/1] drm: check for NULL pointer in drm_gem_object_put Nirmoy Das
2020-05-20 12:19 ` Christian König
2020-05-20 12:49   ` Chris Wilson
2020-05-20 12:54     ` Christian König
2020-05-20 13:00       ` Daniel Vetter
2020-05-20 13:03         ` Christian König
2020-05-20 13:17       ` Chris Wilson
2020-05-20 13:30         ` Emil Velikov
2020-05-20 13:33           ` Emil Velikov
2020-05-20 14:23             ` [PATCH] drm: Restore the NULL check for drm_gem_object_put() Chris Wilson
2020-05-20 14:25               ` Emil Velikov
2020-05-20 16:37                 ` Chris Wilson

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