From 38ab012f109caf10f471db1adf284e620dd8d701 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Tue, 20 Nov 2018 09:39:30 +0800 Subject: KVM: LAPIC: Fix pv ipis use-before-initialization MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Reported by syzkaller: BUG: unable to handle kernel NULL pointer dereference at 0000000000000014 PGD 800000040410c067 P4D 800000040410c067 PUD 40410d067 PMD 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 3 PID: 2567 Comm: poc Tainted: G OE 4.19.0-rc5 #16 RIP: 0010:kvm_pv_send_ipi+0x94/0x350 [kvm] Call Trace: kvm_emulate_hypercall+0x3cc/0x700 [kvm] handle_vmcall+0xe/0x10 [kvm_intel] vmx_handle_exit+0xc1/0x11b0 [kvm_intel] vcpu_enter_guest+0x9fb/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 apic map has not yet been initialized, the testcase triggers pv_send_ipi interface by vmcall which results in kvm->arch.apic_map is dereferenced. This patch fixes it by checking whether or not apic map is NULL and bailing out immediately if that is the case. Fixes: 4180bf1b65 (KVM: X86: Implement "send IPI" hypercall) Reported-by: Wei Wu Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Wei Wu Signed-off-by: Wanpeng Li Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/x86/kvm/lapic.c') diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 89db20f8cb70..02f2291dcf7e 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -576,6 +576,11 @@ int kvm_pv_send_ipi(struct kvm *kvm, unsigned long ipi_bitmap_low, rcu_read_lock(); map = rcu_dereference(kvm->arch.apic_map); + if (unlikely(!map)) { + count = -EOPNOTSUPP; + goto out; + } + if (min > map->max_apic_id) goto out; /* Bits above cluster_size are masked in the caller. */ -- cgit From 354cb410d87314e2eda344feea84809e4261570a Mon Sep 17 00:00:00 2001 From: Yi Wang Date: Thu, 8 Nov 2018 16:48:36 +0800 Subject: KVM: x86: fix empty-body warnings MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We get the following warnings about empty statements when building with 'W=1': arch/x86/kvm/lapic.c:632:53: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] arch/x86/kvm/lapic.c:1907:42: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] arch/x86/kvm/lapic.c:1936:65: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] arch/x86/kvm/lapic.c:1975:44: warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body] Rework the debug helper macro to get rid of these warnings. Signed-off-by: Yi Wang Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm/lapic.c') diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 02f2291dcf7e..c4533d05c214 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -55,7 +55,7 @@ #define PRIo64 "o" /* #define apic_debug(fmt,arg...) printk(KERN_WARNING fmt,##arg) */ -#define apic_debug(fmt, arg...) +#define apic_debug(fmt, arg...) do {} while (0) /* 14 is the version for Xeon and Pentium 8.4.8*/ #define APIC_VERSION (0x14UL | ((KVM_APIC_LVT_NUM - 1) << 16)) -- cgit