From b689e86c9a8f81aa80f2ab8a4d5a4635f870af4b Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 17 Nov 2016 15:55:46 +0100 Subject: [PATCH] KVM: x86: fix missed SRCU usage in kvm_lapic_set_vapic_addr MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 7301d6abaea926d685832f7e1f0c37dd206b01f4 upstream. Reported by syzkaller: [ INFO: suspicious RCU usage. ] 4.9.0-rc4+ #47 Not tainted ------------------------------- ./include/linux/kvm_host.h:536 suspicious rcu_dereference_check() usage! stack backtrace: CPU: 1 PID: 6679 Comm: syz-executor Not tainted 4.9.0-rc4+ #47 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 ffff880039e2f6d0 ffffffff81c2e46b ffff88003e3a5b40 0000000000000000 0000000000000001 ffffffff83215600 ffff880039e2f700 ffffffff81334ea9 ffffc9000730b000 0000000000000004 ffff88003c4f8420 ffff88003d3f8000 Call Trace: [< inline >] __dump_stack lib/dump_stack.c:15 [] dump_stack+0xb3/0x118 lib/dump_stack.c:51 [] lockdep_rcu_suspicious+0x139/0x180 kernel/locking/lockdep.c:4445 [< inline >] __kvm_memslots include/linux/kvm_host.h:534 [< inline >] kvm_memslots include/linux/kvm_host.h:541 [] kvm_gfn_to_hva_cache_init+0xa1e/0xce0 virt/kvm/kvm_main.c:1941 [] kvm_lapic_set_vapic_addr+0xed/0x140 arch/x86/kvm/lapic.c:2217 Reported-by: Dmitry Vyukov Fixes: fda4e2e85589191b123d31cdc21fd33ee70f50fd Cc: Andrew Honig Signed-off-by: Paolo Bonzini Reviewed-by: David Hildenbrand Signed-off-by: Radim Krčmář Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 685ef431a41d..2a04b5fa28c2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3317,6 +3317,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp, }; case KVM_SET_VAPIC_ADDR: { struct kvm_vapic_addr va; + int idx; r = -EINVAL; if (!lapic_in_kernel(vcpu)) @@ -3324,7 +3325,9 @@ long kvm_arch_vcpu_ioctl(struct file *filp, r = -EFAULT; if (copy_from_user(&va, argp, sizeof va)) goto out; + idx = srcu_read_lock(&vcpu->kvm->srcu); r = kvm_lapic_set_vapic_addr(vcpu, va.vapic_addr); + srcu_read_unlock(&vcpu->kvm->srcu, idx); break; } case KVM_X86_SETUP_MCE: { -- 2.20.1