KVM: CVE-2018-19407

KVM: X86: Fix scan ioapic use-before-initialization

References:
https://nvd.nist.gov/vuln/detail/CVE-2018-19407
https://lkml.org/lkml/2018/11/20/580

Change-Id: I25db67cd123956dbcf240a99f316e914c283d0e2
Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>

1 files changed, 112 insertions, 0 deletions

diff --git a/patches/cve/CVE-2018-19407-KVM-X86-Fix-scan-ioapic-use-before-initialization.patch b/patches/cve/CVE-2018-19407-KVM-X86-Fix-scan-ioapic-use-before-initialization.patch
new file mode 100644
index 0000000..55cc7e4
--- /dev/null
+++ b/patches/cve/CVE-2018-19407-KVM-X86-Fix-scan-ioapic-use-before-initialization.patch
@@ -0,0 +1,112 @@
+From 83f00ab9a7c03e9f1410727d985b7fe9473002e1 Mon Sep 17 00:00:00 2001
+From: Wanpeng Li <wanpengli@tencent.com>
+Date: Tue, 20 Nov 2018 16:34:18 +0800
+Subject: [PATCH] KVM: X86: Fix scan ioapic use-before-initialization
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+commit e97f852fd4561e77721bb9a4e0ea9d98305b1e93 upstream.
+
+Reported by syzkaller:
+
+ BUG: unable to handle kernel NULL pointer dereference at 00000000000001c8
+ PGD 80000003ec4da067 P4D 80000003ec4da067 PUD 3f7bfa067 PMD 0
+ Oops: 0000 [#1] PREEMPT SMP PTI
+ CPU: 7 PID: 5059 Comm: debug Tainted: G           OE     4.19.0-rc5 #16
+ RIP: 0010:__lock_acquire+0x1a6/0x1990
+ Call Trace:
+  lock_acquire+0xdb/0x210
+  _raw_spin_lock+0x38/0x70
+  kvm_ioapic_scan_entry+0x3e/0x110 [kvm]
+  vcpu_enter_guest+0x167e/0x1910 [kvm]
+  kvm_arch_vcpu_ioctl_run+0x35c/0x610 [kvm]
+  kvm_vcpu_ioctl+0x3e9/0x6d0 [kvm]
+  do_vfs_ioctl+0xa5/0x690
+  ksys_ioctl+0x6d/0x80
+  __x64_sys_ioctl+0x1a/0x20
+  do_syscall_64+0x83/0x6e0
+  entry_SYSCALL_64_after_hwframe+0x49/0xbe
+
+The reason is that the testcase writes hyperv synic HV_X64_MSR_SINT6 msr
+and triggers scan ioapic logic to load synic vectors into EOI exit bitmap.
+However, irqchip is not initialized by this simple testcase, ioapic/apic
+objects should not be accessed.
+This can be triggered by the following program:
+
+    #define _GNU_SOURCE
+
+    #include <endian.h>
+    #include <stdint.h>
+    #include <stdio.h>
+    #include <stdlib.h>
+    #include <string.h>
+    #include <sys/syscall.h>
+    #include <sys/types.h>
+    #include <unistd.h>
+
+    uint64_t r[3] = {0xffffffffffffffff, 0xffffffffffffffff, 0xffffffffffffffff};
+
+    int main(void)
+    {
+        syscall(__NR_mmap, 0x20000000, 0x1000000, 3, 0x32, -1, 0);
+        long res = 0;
+        memcpy((void*)0x20000040, "/dev/kvm", 9);
+        res = syscall(__NR_openat, 0xffffffffffffff9c, 0x20000040, 0, 0);
+        if (res != -1)
+                r[0] = res;Backport
+        res = syscall(__NR_ioctl, r[0], 0xae01, 0);
+        if (res != -1)
+                r[1] = res;
+        res = syscall(__NR_ioctl, r[1], 0xae41, 0);
+        if (res != -1)
+                r[2] = res;
+        memcpy(
+                        (void*)0x20000080,
+                        "\x01\x00\x00\x00\x00\x5b\x61\xbb\x96\x00\x00\x40\x00\x00\x00\x00\x01\x00"
+                        "\x08\x00\x00\x00\x00\x00\x0b\x77\xd1\x78\x4d\xd8\x3a\xed\xb1\x5c\x2e\x43"
+                        "\xaa\x43\x39\xd6\xff\xf5\xf0\xa8\x98\xf2\x3e\x37\x29\x89\xde\x88\xc6\x33"
+                        "\xfc\x2a\xdb\xb7\xe1\x4c\xac\x28\x61\x7b\x9c\xa9\xbc\x0d\xa0\x63\xfe\xfe"
+                        "\xe8\x75\xde\xdd\x19\x38\xdc\x34\xf5\xec\x05\xfd\xeb\x5d\xed\x2e\xaf\x22"
+                        "\xfa\xab\xb7\xe4\x42\x67\xd0\xaf\x06\x1c\x6a\x35\x67\x10\x55\xcb",
+                        106);
+        syscall(__NR_ioctl, r[2], 0x4008ae89, 0x20000080);
+        syscall(__NR_ioctl, r[2], 0xae80, 0);
+        return 0;
+    }
+
+This patch fixes it by bailing out scan ioapic if ioapic is not initialized in
+kernel.
+
+CVE: CVE-2018-19407
+Upstream-Status: Backport
+
+Reported-by: Wei Wu <ww9210@gmail.com>
+Cc: Paolo Bonzini <pbonzini@redhat.com>
+Cc: Radim Krčmář <rkrcmar@redhat.com>
+Cc: Wei Wu <ww9210@gmail.com>
+Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
+Cc: stable@vger.kernel.org
+Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Signed-off-by: Andreas Wellving <andreas.wellving@enea.com>
+---
+ arch/x86/kvm/x86.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
+index 7c4d02dba110..f24329659bea 100644
+--- a/arch/x86/kvm/x86.c
++++ b/arch/x86/kvm/x86.c
+@@ -6885,7 +6885,8 @@ static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
+        else {
+                if (kvm_x86_ops->sync_pir_to_irr && vcpu->arch.apicv_active)
+                        kvm_x86_ops->sync_pir_to_irr(vcpu);
+-               kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors);
++               if (ioapic_in_kernel(vcpu->kvm))
++                       kvm_ioapic_scan_entry(vcpu, vcpu->arch.ioapic_handled_vectors);
+        }
+        bitmap_or((ulong *)eoi_exit_bitmap, vcpu->arch.ioapic_handled_vectors,
+                  vcpu_to_synic(vcpu)->vec_bitmap, 256);
+-- 
+2.19.2