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Date:   Mon, 03 Apr 2023 00:57:50 -0700
Message-ID: <00000000000057e9d305f869eaa0@google.com>
Subject: [syzbot] [dri?] general protection fault in drm_crtc_next_vblank_start
From:   syzbot <syzbot+54280c5aea19802490b5@syzkaller.appspotmail.com>
To:     airlied@gmail.com, airlied@redhat.com, christian.koenig@amd.com,
        daniel.vetter@ffwll.ch, daniel@ffwll.ch,
        dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org,
        linux-kernel@vger.kernel.org, linux-media@vger.kernel.org,
        robdclark@chromium.org, sean@poorly.run, sumit.semwal@linaro.org,
        syzkaller-bugs@googlegroups.com, tzimmermann@suse.de
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Hello,

syzbot found the following issue on:

HEAD commit:    a6d9e3034536 Add linux-next specific files for 20230330
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1001d1cdc80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=aceb117f7924508e
dashboard link: https://syzkaller.appspot.com/bug?extid=54280c5aea19802490b5
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13435a2ec80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=139c9c21c80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ec1f900ea929/disk-a6d9e303.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fabbf89c0d22/vmlinux-a6d9e303.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1ed05d6192fa/bzImage-a6d9e303.xz

The issue was bisected to:

commit d39e48ca80c0960b039cb38633957f0040f63e1a
Author: Rob Clark <robdclark@chromium.org>
Date:   Fri Sep 3 18:47:54 2021 +0000

    drm/atomic-helper: Set fence deadline for vblank

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12d260c9c80000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=11d260c9c80000
console output: https://syzkaller.appspot.com/x/log.txt?x=16d260c9c80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+54280c5aea19802490b5@syzkaller.appspotmail.com
Fixes: d39e48ca80c0 ("drm/atomic-helper: Set fence deadline for vblank")

[drm] Initialized udl 0.0.1 20120220 for 1-1:0.0 on minor 2
[drm] Initialized udl on minor 2
udl 1-1:0.0: [drm] *ERROR* Read EDID byte 0 failed err ffffffb9
udl 1-1:0.0: [drm] Cannot find any crtc or sizes
general protection fault, probably for non-canonical address 0xdffffc0000000028: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000140-0x0000000000000147]
CPU: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.3.0-rc4-next-20230330-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: usb_hub_wq hub_event
RIP: 0010:drm_crtc_next_vblank_start+0xb3/0x2b0 drivers/gpu/drm/drm_vblank.c:1003
Code: e8 01 00 00 48 69 db 38 02 00 00 48 b8 00 00 00 00 00 fc ff df 49 03 9d 38 03 00 00 4c 8d ab 44 01 00 00 4c 89 ea 48 c1 ea 03 <0f> b6 14 02 4c 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 67
RSP: 0018:ffffc900000e6bb0 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000028 RSI: ffffffff849f2afb RDI: ffff888079558338
RBP: ffffc900000e6c48 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000010 R12: ffff8880795590d8
R13: 0000000000000144 R14: ffff8880795590d8 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f17191c7688 CR3: 00000000281af000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 set_fence_deadline drivers/gpu/drm/drm_atomic_helper.c:1531 [inline]
 drm_atomic_helper_wait_for_fences+0x1b4/0x780 drivers/gpu/drm/drm_atomic_helper.c:1578
 drm_atomic_helper_commit drivers/gpu/drm/drm_atomic_helper.c:2007 [inline]
 drm_atomic_helper_commit+0x1bd/0x370 drivers/gpu/drm/drm_atomic_helper.c:1979
 drm_atomic_commit+0x20a/0x300 drivers/gpu/drm/drm_atomic.c:1503
 drm_client_modeset_commit_atomic+0x69b/0x7e0 drivers/gpu/drm/drm_client_modeset.c:1045
 drm_client_modeset_commit_locked+0x149/0x580 drivers/gpu/drm/drm_client_modeset.c:1148
 drm_client_modeset_commit+0x51/0x80 drivers/gpu/drm/drm_client_modeset.c:1174
 drm_fb_helper_single_fb_probe drivers/gpu/drm/drm_fb_helper.c:1983 [inline]
 __drm_fb_helper_initial_config_and_unlock+0x118a/0x1510 drivers/gpu/drm/drm_fb_helper.c:2169
 drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:2259 [inline]
 drm_fb_helper_initial_config+0x42/0x60 drivers/gpu/drm/drm_fb_helper.c:2251
 drm_fbdev_generic_client_hotplug+0x1ab/0x270 drivers/gpu/drm/drm_fbdev_generic.c:281
 drm_fbdev_generic_setup+0x127/0x3b0 drivers/gpu/drm/drm_fbdev_generic.c:343
 udl_usb_probe+0x120/0x190 drivers/gpu/drm/udl/udl_drv.c:120
 usb_probe_interface+0x30f/0x960 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:579 [inline]
 really_probe+0x240/0xca0 drivers/base/dd.c:658
 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:795
 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:825
 __device_attach_driver+0x1d4/0x2e0 drivers/base/dd.c:953
 bus_for_each_drv+0x149/0x1d0 drivers/base/bus.c:457
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1025
 bus_probe_device+0x17c/0x1c0 drivers/base/bus.c:532
 device_add+0x11c4/0x1c50 drivers/base/core.c:3616
 usb_set_configuration+0x10ee/0x1af0 drivers/usb/core/message.c:2171
 usb_generic_driver_probe+0xcf/0x130 drivers/usb/core/generic.c:238
 usb_probe_device+0xd8/0x2c0 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:579 [inline]
 really_probe+0x240/0xca0 drivers/base/dd.c:658
 __driver_probe_device+0x1df/0x4d0 drivers/base/dd.c:795
 driver_probe_device+0x4c/0x1a0 drivers/base/dd.c:825
 __device_attach_driver+0x1d4/0x2e0 drivers/base/dd.c:953
 bus_for_each_drv+0x149/0x1d0 drivers/base/bus.c:457
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1025
 bus_probe_device+0x17c/0x1c0 drivers/base/bus.c:532
 device_add+0x11c4/0x1c50 drivers/base/core.c:3616
 usb_new_device+0xcb2/0x19d0 drivers/usb/core/hub.c:2575
 hub_port_connect drivers/usb/core/hub.c:5407 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5551 [inline]
 port_event drivers/usb/core/hub.c:5711 [inline]
 hub_event+0x2d9e/0x4e40 drivers/usb/core/hub.c:5793
 process_one_work+0x99a/0x15e0 kernel/workqueue.c:2405
 worker_thread+0x67d/0x10c0 kernel/workqueue.c:2552
 kthread+0x33e/0x440 kernel/kthread.c:379
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:drm_crtc_next_vblank_start+0xb3/0x2b0 drivers/gpu/drm/drm_vblank.c:1003
Code: e8 01 00 00 48 69 db 38 02 00 00 48 b8 00 00 00 00 00 fc ff df 49 03 9d 38 03 00 00 4c 8d ab 44 01 00 00 4c 89 ea 48 c1 ea 03 <0f> b6 14 02 4c 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 67
RSP: 0018:ffffc900000e6bb0 EFLAGS: 00010207
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000028 RSI: ffffffff849f2afb RDI: ffff888079558338
RBP: ffffc900000e6c48 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000010 R12: ffff8880795590d8
R13: 0000000000000144 R14: ffff8880795590d8 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f17191c7688 CR3: 000000002b398000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	e8 01 00 00 48       	callq  0x48000006
   5:	69 db 38 02 00 00    	imul   $0x238,%ebx,%ebx
   b:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  12:	fc ff df
  15:	49 03 9d 38 03 00 00 	add    0x338(%r13),%rbx
  1c:	4c 8d ab 44 01 00 00 	lea    0x144(%rbx),%r13
  23:	4c 89 ea             	mov    %r13,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	0f b6 14 02          	movzbl (%rdx,%rax,1),%edx <-- trapping instruction
  2e:	4c 89 e8             	mov    %r13,%rax
  31:	83 e0 07             	and    $0x7,%eax
  34:	83 c0 03             	add    $0x3,%eax
  37:	38 d0                	cmp    %dl,%al
  39:	7c 08                	jl     0x43
  3b:	84 d2                	test   %dl,%dl
  3d:	0f                   	.byte 0xf
  3e:	85                   	.byte 0x85
  3f:	67                   	addr32


---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches