From: Waiman Long <longman@redhat.com>
To: Juergen Gross <jgross@suse.com>,
Alok Kataria <akataria@vmware.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will.deacon@arm.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Paolo Bonzini <pbonzini@redhat.com>,
Waiman Long <longman@redhat.com>
Subject: [PATCH] x86/paravirt: Guard against invalid cpu # in pv_vcpu_is_preempted()
Date: Mon, 25 Mar 2019 11:57:06 -0400 [thread overview]
Message-ID: <20190325155706.26987-1-longman@redhat.com> (raw)
It was found that passing an invalid cpu number to pv_vcpu_is_preempted()
might panic the kernel in a VM guest. For example,
[ 2.531077] Oops: 0000 [#1] SMP PTI
:
[ 2.532545] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
[ 2.533321] RIP: 0010:__raw_callee_save___kvm_vcpu_is_preempted+0x0/0x20
To guard against this kind of kernel panic, check is added to
pv_vcpu_is_preempted() to make sure that no invalid cpu number will
be used.
Signed-off-by: Waiman Long <longman@redhat.com>
---
arch/x86/include/asm/paravirt.h | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index c25c38a05c1c..4cfb465dcde4 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -671,6 +671,12 @@ static __always_inline void pv_kick(int cpu)
static __always_inline bool pv_vcpu_is_preempted(long cpu)
{
+ /*
+ * Guard against invalid cpu number or the kernel might panic.
+ */
+ if (WARN_ON_ONCE((unsigned long)cpu >= nr_cpu_ids))
+ return false;
+
return PVOP_CALLEE1(bool, lock.vcpu_is_preempted, cpu);
}
--
2.18.1
next reply other threads:[~2019-03-25 15:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-25 15:57 Waiman Long [this message]
2019-03-25 16:40 ` [PATCH] x86/paravirt: Guard against invalid cpu # in pv_vcpu_is_preempted() Juergen Gross
2019-03-25 18:03 ` Waiman Long
2019-04-01 6:38 ` Juergen Gross
2019-04-01 14:01 ` Waiman Long
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