Re: [syzbot] BUG: unable to handle kernel paging request in drm_fb_helper_damage_work (2)

[Borislav Petkov <bp@alien8.de>]

Looks DRM to me. CCed...

On Mon, May 31, 2021 at 12:13:22AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    7ac3a1c1 Merge tag 'mtd/fixes-for-5.13-rc4' of git://git.k..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1619b4b5d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=266cda122a0b56c
> dashboard link: https://syzkaller.appspot.com/bug?extid=545dc60af42828d1e70b
> userspace arch: i386
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+545dc60af42828d1e70b@syzkaller.appspotmail.com
> 
> BUG: unable to handle page fault for address: ffffc9000dc68008
> #PF: supervisor write access in kernel mode
> #PF: error_code(0x0002) - not-present page
> PGD 11000067 P4D 11000067 PUD 111b3067 PMD 1ba2c067 PTE 0
> Oops: 0002 [#1] PREEMPT SMP KASAN
> CPU: 2 PID: 16890 Comm: kworker/2:36 Not tainted 5.13.0-rc3-syzkaller #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
> Workqueue: events drm_fb_helper_damage_work
> RIP: 0010:rep_movs arch/x86/lib/iomem.c:12 [inline]
> RIP: 0010:memcpy_toio+0x83/0xe0 arch/x86/lib/iomem.c:57
> Code: 8c fd 49 89 dd 31 ff 41 83 e5 02 4c 89 ee e8 c4 c2 8c fd 4d 85 ed 75 2e e8 9a ba 8c fd 48 89 e9 48 89 df 4c 89 e6 48 c1 e9 02 <f3> a5 40 f6 c5 02 74 02 66 a5 40 f6 c5 01 74 01 a4 5b 5d 41 5c 41
> RSP: 0018:ffffc9000e73fbc8 EFLAGS: 00010202
> RAX: 0000000000000000 RBX: ffffc9000dc68008 RCX: 00000000000000fe
> RDX: ffff888015340000 RSI: ffffc9000bdd9008 RDI: ffffc9000dc68008
> RBP: 00000000000003f8 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffffff83e81e1c R11: 0000000000000000 R12: ffffc9000bdd9008
> R13: 0000000000000000 R14: ffffc9000bdd9008 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffc9000dc68008 CR3: 000000006c062000 CR4: 0000000000152ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  dma_buf_map_memcpy_to include/linux/dma-buf-map.h:245 [inline]
>  drm_fb_helper_damage_blit_real drivers/gpu/drm/drm_fb_helper.c:388 [inline]
>  drm_fb_helper_damage_blit drivers/gpu/drm/drm_fb_helper.c:419 [inline]
>  drm_fb_helper_damage_work+0x733/0xac0 drivers/gpu/drm/drm_fb_helper.c:450
>  process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
>  worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
>  kthread+0x3b1/0x4a0 kernel/kthread.c:313
>  ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> Modules linked in:
> CR2: ffffc9000dc68008
> ---[ end trace 7f8625a9b15be223 ]---
> RIP: 0010:rep_movs arch/x86/lib/iomem.c:12 [inline]
> RIP: 0010:memcpy_toio+0x83/0xe0 arch/x86/lib/iomem.c:57
> Code: 8c fd 49 89 dd 31 ff 41 83 e5 02 4c 89 ee e8 c4 c2 8c fd 4d 85 ed 75 2e e8 9a ba 8c fd 48 89 e9 48 89 df 4c 89 e6 48 c1 e9 02 <f3> a5 40 f6 c5 02 74 02 66 a5 40 f6 c5 01 74 01 a4 5b 5d 41 5c 41
> RSP: 0018:ffffc9000e73fbc8 EFLAGS: 00010202
> RAX: 0000000000000000 RBX: ffffc9000dc68008 RCX: 00000000000000fe
> RDX: ffff888015340000 RSI: ffffc9000bdd9008 RDI: ffffc9000dc68008
> RBP: 00000000000003f8 R08: 0000000000000000 R09: 0000000000000001
> R10: ffffffff83e81e1c R11: 0000000000000000 R12: ffffc9000bdd9008
> R13: 0000000000000000 R14: ffffc9000bdd9008 R15: 0000000000000001
> FS:  0000000000000000(0000) GS:ffff88802cc00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffc9000dc68008 CR3: 000000006c062000 CR4: 0000000000152ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
> 
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-- 
Regards/Gruss,
    Boris.

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