Hello,
syzbot found the following issue on:
HEAD commit: f9006d9269ea Add linux-next specific files for 20220321
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=101191bd700000
kernel config: https://syzkaller.appspot.com/x/.config?x=c1619ffa2b0259a1
dashboard link: https://syzkaller.appspot.com/bug?extid=717ed82268812a643b28
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=109e8f5d700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1666180b700000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
general protection fault, probably for non-canonical address 0xdffffc0000000038: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000001c0-0x00000000000001c7]
CPU: 0 PID: 3614 Comm: syz-executor358 Tainted: G W 5.17.0-next-20220321-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:flush_workqueue+0xf8/0x1440 kernel/workqueue.c:2828
Code: ff 89 de e8 ea 02 2c 00 84 db 0f 84 28 0f 00 00 e8 fd fe 2b 00 48 8b 85 e8 fe ff ff 48 8d b8 c0 01 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 74 08 3c 03 0f 8e f9 12 00 00 48 8b 85 e8 fe
RSP: 0018:ffffc90003affba8 EFLAGS: 00010202
RAX: 0000000000000038 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff8880184b57c0 RSI: ffffffff814caa33 RDI: 00000000000001c0
RBP: ffffc90003affd18 R08: 0000000000000002 R09: 0000000000000001
R10: ffffffff814caa26 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffc90003affd70 R14: ffffc90003b29000 R15: ffffc90003b2a240
FS: 00007f26eaecd700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020404030 CR3: 00000000246a9000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
kvm_mmu_uninit_tdp_mmu+0x7f/0x170 arch/x86/kvm/mmu/tdp_mmu.c:51
kvm_arch_destroy_vm+0x350/0x470 arch/x86/kvm/x86.c:11799
kvm_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1144 [inline]
kvm_dev_ioctl_create_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:4736 [inline]
kvm_dev_ioctl+0x104d/0x1c00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4791
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f26eaf5dac9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 11 15 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f26eaecd308 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f26eafe5448 RCX: 00007f26eaf5dac9
RDX: 0000000000000000 RSI: 000000000000ae01 RDI: 0000000000000005
RBP: 00007f26eafe5440 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f26eafe544c
R13: 00007f26eafb3074 R14: 6d766b2f7665642f R15: 0000000000022000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:flush_workqueue+0xf8/0x1440 kernel/workqueue.c:2828
Code: ff 89 de e8 ea 02 2c 00 84 db 0f 84 28 0f 00 00 e8 fd fe 2b 00 48 8b 85 e8 fe ff ff 48 8d b8 c0 01 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 20 84 c0 74 08 3c 03 0f 8e f9 12 00 00 48 8b 85 e8 fe
RSP: 0018:ffffc90003affba8 EFLAGS: 00010202
RAX: 0000000000000038 RBX: 0000000000000001 RCX: 0000000000000000
RDX: ffff8880184b57c0 RSI: ffffffff814caa33 RDI: 00000000000001c0
RBP: ffffc90003affd18 R08: 0000000000000002 R09: 0000000000000001
R10: ffffffff814caa26 R11: 0000000000000000 R12: dffffc0000000000
R13: ffffc90003affd70 R14: ffffc90003b29000 R15: ffffc90003b2a240
FS: 00007f26eaecd700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020404030 CR3: 00000000246a9000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: ff 89 de e8 ea 02 decl 0x2eae8de(%rcx)
6: 2c 00 sub $0x0,%al
8: 84 db test %bl,%bl
a: 0f 84 28 0f 00 00 je 0xf38
10: e8 fd fe 2b 00 callq 0x2bff12
15: 48 8b 85 e8 fe ff ff mov -0x118(%rbp),%rax
1c: 48 8d b8 c0 01 00 00 lea 0x1c0(%rax),%rdi
23: 48 89 f8 mov %rdi,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 20 movzbl (%rax,%r12,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 74 08 je 0x3b
33: 3c 03 cmp $0x3,%al
35: 0f 8e f9 12 00 00 jle 0x1334
3b: 48 rex.W
3c: 8b .byte 0x8b
3d: 85 e8 test %ebp,%eax
3f: fe .byte 0xfe
---
This report is generated by a bot. It may contain errors.
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On 3/25/22 16:10, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: f9006d9269ea Add linux-next specific files for 20220321
> git tree: linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=101191bd700000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c1619ffa2b0259a1
> dashboard link: https://syzkaller.appspot.com/bug?extid=717ed82268812a643b28
> 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=109e8f5d700000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1666180b700000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: [email protected]
>
The following code is not safe:
arch/x86/kvm/mmu/tdp_mmu.c:
28 kvm->arch.tdp_mmu_zap_wq =
29 alloc_workqueue("kvm", WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE, 0);
30
31 return true;
Looks like kvm_mmu_init_tdp_mmu() error value is just ignored, and then
all kvm_*_init_vm() functions are void, so the easiest solution is to
check that tdp_mmu_zap_wq is valid pointer
#syz test:
git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
With regards,
Pavel Skripkin
Hello,
syzbot has tested the proposed patch and the reproducer did not trigger any issue:
Reported-and-tested-by: [email protected]
Tested on:
commit: fd4fbb99 Add linux-next specific files for 20220325
git tree: linux-next
kernel config: https://syzkaller.appspot.com/x/.config?x=88d1370cc1f241e6
dashboard link: https://syzkaller.appspot.com/bug?extid=717ed82268812a643b28
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
patch: https://syzkaller.appspot.com/x/patch.diff?x=14f79871700000
Note: testing is done by a robot and is best-effort only.