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authorP J P <ppandit@redhat.com>2015-12-18 11:35:07 +0530
committerPaolo Bonzini <pbonzini@redhat.com>2016-01-15 18:58:01 +0100
commit4c1396cb576c9b14425558b73de1584c7a9735d7 (patch)
tree8f15067c7bce14a79411ff188dd2ea8c2e9e5a86 /hw
parent76c64d33601a4948d6f72022992574a75b6fab97 (diff)
i386: avoid null pointer dereference
Hello, A null pointer dereference issue was reported by Mr Ling Liu, CC'd here. It occurs while doing I/O port write operations via hmp interface. In that, 'current_cpu' remains null as it is not called from cpu_exec loop, which results in the said issue. Below is a proposed (tested)patch to fix this issue; Does it look okay? === From ae88a4947fab9a148cd794f8ad2d812e7f5a1d0f Mon Sep 17 00:00:00 2001 From: Prasad J Pandit <pjp@fedoraproject.org> Date: Fri, 18 Dec 2015 11:16:07 +0530 Subject: [PATCH] i386: avoid null pointer dereference When I/O port write operation is called from hmp interface, 'current_cpu' remains null, as it is not called from cpu_exec() loop. This leads to a null pointer dereference in vapic_write routine. Add check to avoid it. Reported-by: Ling Liu <liuling-it@360.cn> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org> Message-Id: <alpine.LFD.2.20.1512181129320.9805@wniryva> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: P J P <ppandit@redhat.com>
Diffstat (limited to 'hw')
-rw-r--r--hw/i386/kvmvapic.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
index c6d34b2546..f0922da682 100644
--- a/hw/i386/kvmvapic.c
+++ b/hw/i386/kvmvapic.c
@@ -634,13 +634,18 @@ static int vapic_prepare(VAPICROMState *s)
static void vapic_write(void *opaque, hwaddr addr, uint64_t data,
unsigned int size)
{
- CPUState *cs = current_cpu;
- X86CPU *cpu = X86_CPU(cs);
- CPUX86State *env = &cpu->env;
- hwaddr rom_paddr;
VAPICROMState *s = opaque;
+ X86CPU *cpu;
+ CPUX86State *env;
+ hwaddr rom_paddr;
- cpu_synchronize_state(cs);
+ if (!current_cpu) {
+ return;
+ }
+
+ cpu_synchronize_state(current_cpu);
+ cpu = X86_CPU(current_cpu);
+ env = &cpu->env;
/*
* The VAPIC supports two PIO-based hypercalls, both via port 0x7E.