diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2016-06-01 15:09:23 +0300 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2016-08-23 00:37:13 +0300 |
| commit | 50ebd5b3703252b55c27be318bf81028350a45b5 (patch) | |
| tree | be5cbeef3cb8c7d2a17eb42299ea92f98992c44e /arch/x86/kvm | |
| parent | d7f02d287db8cbe77560837daac39911a71537f9 (diff) | |
| download | linux-50ebd5b3703252b55c27be318bf81028350a45b5.tar.xz | |
KVM: x86: fix OOPS after invalid KVM_SET_DEBUGREGS
commit d14bdb553f9196169f003058ae1cdabe514470e6 upstream.
MOV to DR6 or DR7 causes a #GP if an attempt is made to write a 1 to
any of bits 63:32. However, this is not detected at KVM_SET_DEBUGREGS
time, and the next KVM_RUN oopses:
general protection fault: 0000 [#1] SMP
CPU: 2 PID: 14987 Comm: a.out Not tainted 4.4.9-300.fc23.x86_64 #1
Hardware name: LENOVO 2325F51/2325F51, BIOS G2ET32WW (1.12 ) 05/30/2012
[...]
Call Trace:
[<ffffffffa072c93d>] kvm_arch_vcpu_ioctl_run+0x141d/0x14e0 [kvm]
[<ffffffffa071405d>] kvm_vcpu_ioctl+0x33d/0x620 [kvm]
[<ffffffff81241648>] do_vfs_ioctl+0x298/0x480
[<ffffffff812418a9>] SyS_ioctl+0x79/0x90
[<ffffffff817a0f2e>] entry_SYSCALL_64_fastpath+0x12/0x71
Code: 55 83 ff 07 48 89 e5 77 27 89 ff ff 24 fd 90 87 80 81 0f 23 fe 5d c3 0f 23 c6 5d c3 0f 23 ce 5d c3 0f 23 d6 5d c3 0f 23 de 5d c3 <0f> 23 f6 5d c3 0f 0b 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00
RIP [<ffffffff810639eb>] native_set_debugreg+0x2b/0x40
RSP <ffff88005836bd50>
Testcase (beautified/reduced from syzkaller output):
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <stdint.h>
#include <linux/kvm.h>
#include <fcntl.h>
#include <sys/ioctl.h>
long r[8];
int main()
{
struct kvm_debugregs dr = { 0 };
r[2] = open("/dev/kvm", O_RDONLY);
r[3] = ioctl(r[2], KVM_CREATE_VM, 0);
r[4] = ioctl(r[3], KVM_CREATE_VCPU, 7);
memcpy(&dr,
"\x5d\x6a\x6b\xe8\x57\x3b\x4b\x7e\xcf\x0d\xa1\x72"
"\xa3\x4a\x29\x0c\xfc\x6d\x44\x00\xa7\x52\xc7\xd8"
"\x00\xdb\x89\x9d\x78\xb5\x54\x6b\x6b\x13\x1c\xe9"
"\x5e\xd3\x0e\x40\x6f\xb4\x66\xf7\x5b\xe3\x36\xcb",
48);
r[7] = ioctl(r[4], KVM_SET_DEBUGREGS, &dr);
r[6] = ioctl(r[4], KVM_RUN, 0);
}
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/x86.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a7fd5b336ac7..4ae334a1bd99 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2952,6 +2952,11 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu, if (dbgregs->flags) return -EINVAL; + if (dbgregs->dr6 & ~0xffffffffull) + return -EINVAL; + if (dbgregs->dr7 & ~0xffffffffull) + return -EINVAL; + memcpy(vcpu->arch.db, dbgregs->db, sizeof(vcpu->arch.db)); vcpu->arch.dr6 = dbgregs->dr6; vcpu->arch.dr7 = dbgregs->dr7; |