From 7834349cfcc68b946c0d241ffd99c598857e489b Mon Sep 17 00:00:00 2001 From: Eduardo Habkost Date: Wed, 14 Oct 2009 15:02:27 -0300 Subject: [PATCH] fix MSR_COUNT for kvm_arch_save_regs() A new register was added to the load/save list on commit d283d5a65a2bdcc570065267be21848bd6fe3d78, but MSR_COUNT was not updated, leading to potential stack corruption on kvm_arch_save_regs(). The following registers are saved by kvm_arch_save_regs(): 1) MSR_IA32_SYSENTER_CS 2) MSR_IA32_SYSENTER_ESP 3) MSR_IA32_SYSENTER_EIP 4) MSR_STAR 5) MSR_IA32_TSC 6) MSR_VM_HSAVE_PA 7) MSR_CSTAR (x86_64 only) 8) MSR_KERNELGSBASE (x86_64 only) 9) MSR_FMASK (x86_64 only) 10) MSR_LSTAR (x86_64 only) (cherry picked from commit e7e5448ba387adc20be1cf08411a5b526d684299) Signed-off-by: Eduardo Habkost Signed-off-by: Marcelo Tosatti Signed-off-by: Mark McLoughlin Fedora-patch: qemu-fix-msr-count-potential-segfault.patch --- qemu-kvm-x86.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c index 492dbc5..d5436b6 100644 --- a/qemu-kvm-x86.c +++ b/qemu-kvm-x86.c @@ -847,9 +847,9 @@ static int get_msr_entry(struct kvm_msr_entry *entry, CPUState *env) } #ifdef TARGET_X86_64 -#define MSR_COUNT 9 +#define MSR_COUNT 10 #else -#define MSR_COUNT 5 +#define MSR_COUNT 6 #endif static void set_v8086_seg(struct kvm_segment *lhs, const SegmentCache *rhs) @@ -991,6 +991,7 @@ void kvm_arch_load_regs(CPUState *env) /* msrs */ n = 0; + /* Remember to increase MSR_COUNT if you add new registers below */ set_msr_entry(&msrs[n++], MSR_IA32_SYSENTER_CS, env->sysenter_cs); set_msr_entry(&msrs[n++], MSR_IA32_SYSENTER_ESP, env->sysenter_esp); set_msr_entry(&msrs[n++], MSR_IA32_SYSENTER_EIP, env->sysenter_eip); @@ -1166,6 +1167,7 @@ void kvm_arch_save_regs(CPUState *env) /* msrs */ n = 0; + /* Remember to increase MSR_COUNT if you add new registers below */ msrs[n++].index = MSR_IA32_SYSENTER_CS; msrs[n++].index = MSR_IA32_SYSENTER_ESP; msrs[n++].index = MSR_IA32_SYSENTER_EIP; -- 1.6.2.5