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 <p...@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...@360.cn>
Signed-off-by: Prasad J Pandit <p...@fedoraproject.org>
---
hw/i386/kvmvapic.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
index c6d34b2..18157c7 100644
--- a/hw/i386/kvmvapic.c
+++ b/hw/i386/kvmvapic.c
@@ -634,6 +634,10 @@ static int vapic_prepare(VAPICROMState *s)
static void vapic_write(void *opaque, hwaddr addr, uint64_t data,
unsigned int size)
{
+ if (!current_cpu) {
+ return;
+ }
+
CPUState *cs = current_cpu;
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
--
2.4.3
===
Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
47AF CE69 3A90 54AA 9045 1053 DD13 3D32 FE5B 041F
