Re: kvm: WARNING in kvm_apic_accept_events

Dmitry Vyukov
2016-01-15T17:13:00Z

On Fri, Jan 8, 2016 at 6:16 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> Hello,
>
> The following program triggers WARNING in kvm_apic_accept_events:
>
> // autogenerated by syzkaller (http://github.com/google/syzkaller)
> #include <unistd.h>
> #include <sys/syscall.h>
> #include <string.h>
> #include <stdint.h>
>
> long r[32];
>
> int main()
> {
> memset(r, -1, sizeof(r));
> r[0] = syscall(SYS_mmap, 0x20000000ul, 0x10000ul, 0x3ul,
> 0x32ul, 0xfffffffffffffffful, 0x0ul);
> memcpy((void*)0x20007000, "\x2f\x64\x65\x76\x2f\x6b\x76\x6d", 8);
> r[2] = syscall(SYS_open, 0x20007000ul, 0x801ul, 0x0ul, 0, 0, 0);
> r[3] = syscall(SYS_ioctl, r[2], 0xae01ul, 0x0ul, 0, 0, 0);
> *(uint64_t*)0x2000cbe8 = (uint64_t)0x2cf6;
> r[5] = syscall(SYS_ioctl, r[3], 0xae78ul, 0x2000cbe8ul, 0, 0, 0);
> r[6] = syscall(SYS_ioctl, r[2], 0xae01ul, 0x0ul, 0, 0, 0);
> r[7] = syscall(SYS_ioctl, r[6], 0xae60ul, 0, 0, 0, 0);
> r[8] = syscall(SYS_ioctl, r[6], 0xae41ul, 0x0ul, 0, 0, 0);
> *(uint8_t*)0x20001f89 = (uint8_t)0xff5b;
> *(uint8_t*)0x20001f8a = (uint8_t)0x8;
> *(uint8_t*)0x20001f8b = (uint8_t)0x7;
> *(uint8_t*)0x20001f8c = (uint8_t)0x8;
> *(uint32_t*)0x20001f8d = (uint32_t)0x2;
> *(uint8_t*)0x20001f91 = (uint8_t)0xfffffffffffffff7;
> *(uint8_t*)0x20001f92 = (uint8_t)0x8;
> *(uint8_t*)0x20001f93 = (uint8_t)0x6;
> *(uint8_t*)0x20001f94 = (uint8_t)0x4e399187;
> *(uint8_t*)0x20001f95 = (uint8_t)0x28;
> *(uint8_t*)0x20001f96 = (uint8_t)0x5;
> *(uint8_t*)0x20001f97 = (uint8_t)0x7;
> *(uint8_t*)0x20001f98 = (uint8_t)0x4;
> *(uint32_t*)0x20001f99 = (uint32_t)0x4;
> *(uint32_t*)0x20001f9d = (uint32_t)0x8;
> *(uint8_t*)0x20001fa1 = (uint8_t)0x1;
> *(uint8_t*)0x20001fa2 = (uint8_t)0x4;
> *(uint8_t*)0x20001fa3 = (uint8_t)0x2;
> *(uint8_t*)0x20001fa4 = (uint8_t)0x5;
> r[28] = syscall(SYS_ioctl, r[8], 0x4040aea0ul, 0x20001f89ul, 0, 0, 0);
> *(uint32_t*)0x2000c000 = (uint32_t)0x2;
> r[30] = syscall(SYS_ioctl, r[8], 0x4004ae99ul, 0x2000c000ul, 0, 0, 0);
> r[31] = syscall(SYS_ioctl, r[8], 0xae80ul, 0, 0, 0, 0);
> return 0;
> }
>
>
> ------------[ cut here ]------------
> WARNING: CPU: 1 PID: 6658 at arch/x86/kvm/lapic.c:2157
> kvm_apic_accept_events+0x3dd/0x440()
> Modules linked in:
> CPU: 1 PID: 6658 Comm: a.out Tainted: G W 4.4.0-rc8+ #216
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> 00000000ffffffff ffff88006c8bf990 ffffffff82904c8d 0000000000000000
> ffff8800624eaf00 ffffffff85ee24a0 ffff88006c8bf9d0 ffffffff8133e979
> ffffffff810d4f0d ffffffff85ee24a0 000000000000086d ffff88006571b608
> Call Trace:
> [< inline >] __dump_stack lib/dump_stack.c:15
> [<ffffffff82904c8d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
> [<ffffffff8133e979>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:460
> [<ffffffff8133eba9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:493
> [<ffffffff810d4f0d>] kvm_apic_accept_events+0x3dd/0x440
> arch/x86/kvm/lapic.c:2157
> [< inline >] vcpu_block arch/x86/kvm/x86.c:6627
> [< inline >] vcpu_run arch/x86/kvm/x86.c:6662
> [<ffffffff81068822>] kvm_arch_vcpu_ioctl_run+0xc32/0x5820
> arch/x86/kvm/x86.c:6818
> [<ffffffff8101cf61>] kvm_vcpu_ioctl+0x5f1/0xd00
> arch/x86/kvm/../../../virt/kvm/kvm_main.c:2375
> [< inline >] vfs_ioctl fs/ioctl.c:43
> [<ffffffff817b36b1>] do_vfs_ioctl+0x681/0xe40 fs/ioctl.c:607
> [< inline >] SYSC_ioctl fs/ioctl.c:622
> [<ffffffff817b3eff>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:613
> [<ffffffff85e745b6>] entry_SYSCALL_64_fastpath+0x16/0x7a
> arch/x86/entry/entry_64.S:185
> ---[ end trace 231a97373e5bf4b0 ]---
>
>
> On commit b06f3a168cdcd80026276898fd1fee443ef25743 (Jan 6).

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