diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0026-KVM-x86-fix-escape-of-guest-dr6-to-the-host.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0026-KVM-x86-fix-escape-of-guest-dr6-to-the-host.patch | 70 |
1 files changed, 0 insertions, 70 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0026-KVM-x86-fix-escape-of-guest-dr6-to-the-host.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0026-KVM-x86-fix-escape-of-guest-dr6-to-the-host.patch deleted file mode 100644 index 38255613..00000000 --- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0026-KVM-x86-fix-escape-of-guest-dr6-to-the-host.patch +++ /dev/null @@ -1,70 +0,0 @@ -From 75a724909e81cd4612490d633ab269495377d332 Mon Sep 17 00:00:00 2001 -From: Wanpeng Li <wanpeng.li@hotmail.com> -Date: Wed, 13 Dec 2017 10:46:40 +0100 -Subject: [PATCH 26/33] KVM: x86: fix escape of guest dr6 to the host -MIME-Version: 1.0 -Content-Type: text/plain; charset=UTF-8 -Content-Transfer-Encoding: 8bit - -commit efdab992813fb2ed825745625b83c05032e9cda2 upstream. - -syzkaller reported: - - WARNING: CPU: 0 PID: 12927 at arch/x86/kernel/traps.c:780 do_debug+0x222/0x250 - CPU: 0 PID: 12927 Comm: syz-executor Tainted: G OE 4.15.0-rc2+ #16 - RIP: 0010:do_debug+0x222/0x250 - Call Trace: - <#DB> - debug+0x3e/0x70 - RIP: 0010:copy_user_enhanced_fast_string+0x10/0x20 - </#DB> - _copy_from_user+0x5b/0x90 - SyS_timer_create+0x33/0x80 - entry_SYSCALL_64_fastpath+0x23/0x9a - -The testcase sets a watchpoint (with perf_event_open) on a buffer that is -passed to timer_create() as the struct sigevent argument. In timer_create(), -copy_from_user()'s rep movsb triggers the BP. The testcase also sets -the debug registers for the guest. - -However, KVM only restores host debug registers when the host has active -watchpoints, which triggers a race condition when running the testcase with -multiple threads. The guest's DR6.BS bit can escape to the host before -another thread invokes timer_create(), and do_debug() complains. - -The fix is to respect do_debug()'s dr6 invariant when leaving KVM. - -Reported-by: Dmitry Vyukov <dvyukov@google.com> -Cc: Paolo Bonzini <pbonzini@redhat.com> -Cc: Radim Krčmář <rkrcmar@redhat.com> -Cc: David Hildenbrand <david@redhat.com> -Cc: Dmitry Vyukov <dvyukov@google.com> -Reviewed-by: David Hildenbrand <david@redhat.com> -Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> -Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> -Signed-off-by: Radim Krčmář <rkrcmar@redhat.com> -Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ---- - arch/x86/kvm/x86.c | 6 ++++++ - 1 file changed, 6 insertions(+) - -diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c -index d2ea523..af333e1 100644 ---- a/arch/x86/kvm/x86.c -+++ b/arch/x86/kvm/x86.c -@@ -2833,6 +2833,12 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu) - kvm_x86_ops->vcpu_put(vcpu); - kvm_put_guest_fpu(vcpu); - vcpu->arch.last_host_tsc = rdtsc(); -+ /* -+ * If userspace has set any breakpoints or watchpoints, dr6 is restored -+ * on every vmexit, but if not, we might have a stale dr6 from the -+ * guest. do_debug expects dr6 to be cleared after it runs, do the same. -+ */ -+ set_debugreg(0, 6); - } - - static int kvm_vcpu_ioctl_get_lapic(struct kvm_vcpu *vcpu, --- -2.7.4 - |