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[94.39.195.126]) by smtp.gmail.com with ESMTPSA id c15sm3103036wmd.19.2016.01.15.08.04.40 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 15 Jan 2016 08:04:40 -0800 (PST) From: Paolo Bonzini To: qemu-devel@nongnu.org Date: Fri, 15 Jan 2016 17:04:19 +0100 Message-Id: <1452873871-138914-5-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1452873871-138914-1-git-send-email-pbonzini@redhat.com> References: <1452873871-138914-1-git-send-email-pbonzini@redhat.com> X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2a00:1450:400c:c09::22f Cc: Prasad J Pandit Subject: [Qemu-devel] [PULL] i386: avoid null pointer dereference X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org X-Spam-Status: No, score=-6.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI, T_DKIM_INVALID, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Prasad J Pandit 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 Signed-off-by: Prasad J Pandit Message-Id: Signed-off-by: Paolo Bonzini --- hw/i386/kvmvapic.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c index c6d34b2..f0922da 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.