From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Naresh Kamboju <naresh.kamboju@linaro.org>
Subject: [PATCH] KVM: X86: Fix dereference null cpufreq policy
Date: Mon, 2 Mar 2020 15:15:36 +0800 [thread overview]
Message-ID: <1583133336-7832-1-git-send-email-wanpengli@tencent.com> (raw)
From: Wanpeng Li <wanpengli@tencent.com>
Naresh Kamboju reported:
Linux version 5.6.0-rc4 (oe-user@oe-host) (gcc version
(GCC)) #1 SMP Sun Mar 1 22:59:08 UTC 2020
kvm: no hardware support
BUG: kernel NULL pointer dereference, address: 000000000000028c
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: 0000 [#1] SMP NOPTI
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc4 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
04/01/2014
RIP: 0010:kobject_put+0x12/0x1c0
Call Trace:
cpufreq_cpu_put+0x15/0x20
kvm_arch_init+0x1f6/0x2b0
kvm_init+0x31/0x290
? svm_check_processor_compat+0xd/0xd
? svm_check_processor_compat+0xd/0xd
svm_init+0x21/0x23
do_one_initcall+0x61/0x2f0
? rdinit_setup+0x30/0x30
? rcu_read_lock_sched_held+0x4f/0x80
kernel_init_freeable+0x219/0x279
? rest_init+0x250/0x250
kernel_init+0xe/0x110
ret_from_fork+0x27/0x50
Modules linked in:
CR2: 000000000000028c
---[ end trace 239abf40c55c409b ]---
RIP: 0010:kobject_put+0x12/0x1c0
cpufreq policy which is get by cpufreq_cpu_get() can be NULL if it is failure,
this patch takes care of it.
Fixes: aaec7c03de (KVM: x86: avoid useless copy of cpufreq policy)
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/x86.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5de2006..3156e25 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7195,10 +7195,12 @@ static void kvm_timer_init(void)
cpu = get_cpu();
policy = cpufreq_cpu_get(cpu);
- if (policy && policy->cpuinfo.max_freq)
- max_tsc_khz = policy->cpuinfo.max_freq;
+ if (policy) {
+ if (policy->cpuinfo.max_freq)
+ max_tsc_khz = policy->cpuinfo.max_freq;
+ cpufreq_cpu_put(policy);
+ }
put_cpu();
- cpufreq_cpu_put(policy);
#endif
cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
--
2.7.4
next reply other threads:[~2020-03-02 7:18 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-02 7:15 Wanpeng Li [this message]
2020-03-02 7:55 ` Paolo Bonzini
2020-03-02 8:12 ` Viresh Kumar
2020-03-02 8:39 ` Paolo Bonzini
2020-03-02 9:14 ` Viresh Kumar
2020-03-02 10:23 ` Paolo Bonzini
2020-03-02 8:58 ` Naresh Kamboju
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