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authorPaolo Bonzini <pbonzini@redhat.com>2016-06-01 14:09:23 +0200
committerSasha Levin <sasha.levin@oracle.com>2016-06-19 23:47:42 -0400
commit26c6a77797c961c345b3d9c2be96f2cbde6276a1 (patch)
tree45c0c8ba2b953aec4dfde921527f4f196839a71f
parent9a579331430c2cebb99488f664a736654988532d (diff)
downloadlinux-linaro-stable-26c6a77797c961c345b3d9c2be96f2cbde6276a1.tar.gz
KVM: x86: fix OOPS after invalid KVM_SET_DEBUGREGS
[ Upstream commit d14bdb553f9196169f003058ae1cdabe514470e6 ] 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> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--arch/x86/kvm/x86.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 160981f69d4f..518c7a8a3121 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3111,6 +3111,11 @@ 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;
kvm_update_dr6(vcpu);