Hello,
syzbot found the following issue on:
HEAD commit: 136057256686 Linux 5.16-rc2 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=14029126b00000 kernel config: https://syzkaller.appspot.com/x/.config?x=bf85c53718a1e697 dashboard link: https://syzkaller.appspot.com/bug?extid=62d1cf88cc39247b2e23 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
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+62d1cf88cc39247b2e23@syzkaller.appspotmail.com
RBP: 00007f96f6d2a1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffde5383b0f R14: 00007f96f6d2a300 R15: 0000000000022000 </TASK> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 3 PID: 32308 Comm: syz-executor.2 Not tainted 5.16.0-rc2-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014 RIP: 0010:virtio_gpu_object_shmem_init drivers/gpu/drm/virtio/virtgpu_object.c:183 [inline] RIP: 0010:virtio_gpu_object_create+0x29b/0xd90 drivers/gpu/drm/virtio/virtgpu_object.c:249 Code: 89 de e8 38 11 09 fd 48 85 db 0f 85 9f 03 00 00 e8 9a 0e 09 fd 49 8d 7f 0c 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 82 RSP: 0018:ffffc90002fafad0 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc900242c8000 RDX: 0000000000000000 RSI: ffffffff846dc446 RDI: 0000000000000000 RBP: ffff8880257af000 R08: 0000000000000000 R09: ffffffff8bcca173 R10: ffffffff846dc438 R11: 0000000000000000 R12: ffffc90002fafbd0 R13: ffff8880430e0010 R14: ffff8880430e0000 R15: fffffffffffffff4 FS: 00007f96f6d2a700(0000) GS:ffff88802cd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000009af988 CR3: 0000000053153000 CR4: 0000000000150ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> virtio_gpu_gem_create drivers/gpu/drm/virtio/virtgpu_gem.c:42 [inline] virtio_gpu_mode_dumb_create+0x319/0x5c0 drivers/gpu/drm/virtio/virtgpu_gem.c:90 drm_mode_create_dumb+0x26c/0x2f0 drivers/gpu/drm/drm_dumb_buffers.c:96 drm_ioctl_kernel+0x27d/0x4e0 drivers/gpu/drm/drm_ioctl.c:782 drm_ioctl+0x51e/0x9d0 drivers/gpu/drm/drm_ioctl.c:885 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f96f97b4ae9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f96f6d2a188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f96f98c7f60 RCX: 00007f96f97b4ae9 RDX: 0000000020000040 RSI: 00000000c02064b2 RDI: 0000000000000003 RBP: 00007f96f6d2a1d0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000002 R13: 00007ffde5383b0f R14: 00007f96f6d2a300 R15: 0000000000022000 </TASK> Modules linked in: ---[ end trace 7991b533e1b66750 ]--- RIP: 0010:virtio_gpu_object_shmem_init drivers/gpu/drm/virtio/virtgpu_object.c:183 [inline] RIP: 0010:virtio_gpu_object_create+0x29b/0xd90 drivers/gpu/drm/virtio/virtgpu_object.c:249 Code: 89 de e8 38 11 09 fd 48 85 db 0f 85 9f 03 00 00 e8 9a 0e 09 fd 49 8d 7f 0c 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 82 RSP: 0018:ffffc90002fafad0 EFLAGS: 00010246 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc900242c8000 RDX: 0000000000000000 RSI: ffffffff846dc446 RDI: 0000000000000000 RBP: ffff8880257af000 R08: 0000000000000000 R09: ffffffff8bcca173 R10: ffffffff846dc438 R11: 0000000000000000 R12: ffffc90002fafbd0 R13: ffff8880430e0010 R14: ffff8880430e0000 R15: fffffffffffffff4 FS: 00007f96f6d2a700(0000) GS:ffff88802cd00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000009af988 CR3: 0000000053153000 CR4: 0000000000150ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 89 de mov %ebx,%esi 2: e8 38 11 09 fd callq 0xfd09113f 7: 48 85 db test %rbx,%rbx a: 0f 85 9f 03 00 00 jne 0x3af 10: e8 9a 0e 09 fd callq 0xfd090eaf 15: 49 8d 7f 0c lea 0xc(%r15),%rdi 19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 20: fc ff df 23: 48 89 fa mov %rdi,%rdx 26: 48 c1 ea 03 shr $0x3,%rdx * 2a: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction 2e: 48 89 f8 mov %rdi,%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: 82 .byte 0x82
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