-non-existent email address On Wed, Aug 9, 2017 at 7:07 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > Hello, > > syzkaller fuzzer has hit the following WARNING in kvm_arch_vcpu_ioctl_run. > This is easily reproducible and reproducer is attached at the bottom. > The report is on upstream commit > 26c5cebfdb6ca799186f1e56be7d6f2480c5012c. This requires setting > kvm-intel.unrestricted_guest=0 on the machine, with > unrestricted_guest=1 the WARNING does not happen. Output of the > program is: > > ret1=0 exit_reason=17 suberror=1 > ret2=0 exit_reason=8 suberror=65530 > > > WARNING: CPU: 1 PID: 2850 at arch/x86/kvm/x86.c:7223 > kvm_arch_vcpu_ioctl_run+0x213/0x5870 arch/x86/kvm/x86.c:7223 > CPU: 1 PID: 2850 Comm: a.out Not tainted 4.13.0-rc3+ #445 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:16 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:52 > panic+0x1e4/0x417 kernel/panic.c:180 > __warn+0x1c4/0x1d9 kernel/panic.c:541 > report_bug+0x211/0x2d0 lib/bug.c:183 > fixup_bug+0x40/0x90 arch/x86/kernel/traps.c:190 > do_trap_no_signal arch/x86/kernel/traps.c:224 [inline] > do_trap+0x260/0x390 arch/x86/kernel/traps.c:273 > do_error_trap+0x120/0x390 arch/x86/kernel/traps.c:310 > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:323 > invalid_op+0x1e/0x30 arch/x86/entry/entry_64.S:846 > RIP: 0010:kvm_arch_vcpu_ioctl_run+0x213/0x5870 arch/x86/kvm/x86.c:7222 > RSP: 0018:ffff8800627cf670 EFLAGS: 00010297 > RAX: ffff880066c44480 RBX: ffff88006b07f000 RCX: ffff880067d0845c > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880067d08260 > RBP: ffff8800627cfa40 R08: 0000000000000001 R09: 0000000000000000 > R10: ffff8800627cfa58 R11: 0000000000000000 R12: 0000000000000001 > R13: 0000000000000000 R14: ffff88006b934880 R15: ffff880067d08040 > kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2592 > vfs_ioctl fs/ioctl.c:45 [inline] > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:685 > SYSC_ioctl fs/ioctl.c:700 [inline] > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691 > entry_SYSCALL_64_fastpath+0x1f/0xbe > RIP: 0033:0x44ccc9 > RSP: 002b:00007f9ecbc37db8 EFLAGS: 00000297 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000044ccc9 > RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005 > RBP: 0000000000000082 R08: 00007f9ecbc38700 R09: 0000000000000000 > R10: 00007f9ecbc38700 R11: 0000000000000297 R12: 0000000000000000 > R13: 0000000000000000 R14: 00007f9ecbc389c0 R15: 00007f9ecbc38700 > > > > // autogenerated by syzkaller (http://github.com/google/syzkaller) > #define _GNU_SOURCE > #include <pthread.h> > #include <stdio.h> > #include <stdlib.h> > #include <string.h> > #include <sys/wait.h> > #include <sys/types.h> > #include <sys/stat.h> > #include <sys/mman.h> > #include <fcntl.h> > #include <unistd.h> > #include <linux/kvm.h> > #include <stdio.h> > > int kvmcpu; > struct kvm_run *run; > > void* thr(void* arg) > { > int res; > res = ioctl(kvmcpu, KVM_RUN, 0); > printf("ret1=%d exit_reason=%d suberror=%d\n", > res, run->exit_reason, run->internal.suberror); > return 0; > } > > void test() > { > int i, kvm, kvmvm; > pthread_t th[4]; > > kvm = open("/dev/kvm", O_RDWR); > kvmvm = ioctl(kvm, KVM_CREATE_VM, 0); > kvmcpu = ioctl(kvmvm, KVM_CREATE_VCPU, 0); > run = (struct kvm_run*)mmap(0, 4096, PROT_READ|PROT_WRITE, > MAP_SHARED, kvmcpu, 0); > srand(getpid()); > for (i = 0; i < 4; i++) { > pthread_create(&th[i], 0, thr, 0); > usleep(rand() % 10000); > } > for (i = 0; i < 4; i++) > pthread_join(th[i], 0); > } > > int main() > { > for (;;) { > int pid = fork(); > if (pid < 0) > exit(1); > if (pid == 0) { > test(); > exit(0); > } > int status; > while (waitpid(pid, &status, __WALL) != pid) {} > } > return 0; > }
