diff options
author | P J P <ppandit@redhat.com> | 2015-12-18 11:35:07 +0530 |
---|---|---|
committer | Paolo Bonzini <pbonzini@redhat.com> | 2016-01-15 18:58:01 +0100 |
commit | 4c1396cb576c9b14425558b73de1584c7a9735d7 (patch) | |
tree | 8f15067c7bce14a79411ff188dd2ea8c2e9e5a86 /hw/i386 | |
parent | 76c64d33601a4948d6f72022992574a75b6fab97 (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/i386')
-rw-r--r-- | hw/i386/kvmvapic.c | 15 |
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. |