aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorIgor Mammedov <imammedo@redhat.com>2013-01-28 12:49:26 +0100
committerGleb Natapov <gleb@redhat.com>2013-01-29 08:57:56 +0200
commitf8bb056564ed719b2fa5e05028bc70aeb0cc5c6c (patch)
tree6ed3ddd6099dd6ee8b7be7aa47a0d2958d97f528
parentf9e90c798dc84be2b0b988517e86b49faf79d5dc (diff)
target-i386: kvm: prevent buffer overflow if -cpu foo, [x]level is too big
Stack corruption may occur if too big 'level' or 'xlevel' values passed on command line with KVM enabled, due to limited size of cpuid_data in kvm_arch_init_vcpu(). reproduces with: qemu -enable-kvm -cpu qemu64,level=4294967295 or qemu -enable-kvm -cpu qemu64,xlevel=4294967295 Check if there is space in cpuid_data before passing it to cpu_x86_cpuid() or abort() if there is not space. Reviewed-by: Laszlo Ersek <lersek@redhat.com> Reviewed-by: Andreas Faerber <afaerber@suse.de> Signed-off-by: Igor Mammedov <imammedo@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com>
-rw-r--r--target-i386/kvm.c25
1 files changed, 24 insertions, 1 deletions
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 3acff40c47..4ecb728a5d 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -411,11 +411,12 @@ static void cpu_update_state(void *opaque, int running, RunState state)
}
}
+#define KVM_MAX_CPUID_ENTRIES 100
int kvm_arch_init_vcpu(CPUState *cs)
{
struct {
struct kvm_cpuid2 cpuid;
- struct kvm_cpuid_entry2 entries[100];
+ struct kvm_cpuid_entry2 entries[KVM_MAX_CPUID_ENTRIES];
} QEMU_PACKED cpuid_data;
X86CPU *cpu = X86_CPU(cs);
CPUX86State *env = &cpu->env;
@@ -502,6 +503,10 @@ int kvm_arch_init_vcpu(CPUState *cs)
cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused);
for (i = 0; i <= limit; i++) {
+ if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
+ fprintf(stderr, "unsupported level value: 0x%x\n", limit);
+ abort();
+ }
c = &cpuid_data.entries[cpuid_i++];
switch (i) {
@@ -516,6 +521,11 @@ int kvm_arch_init_vcpu(CPUState *cs)
times = c->eax & 0xff;
for (j = 1; j < times; ++j) {
+ if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
+ fprintf(stderr, "cpuid_data is full, no space for "
+ "cpuid(eax:2):eax & 0xf = 0x%x\n", times);
+ abort();
+ }
c = &cpuid_data.entries[cpuid_i++];
c->function = i;
c->flags = KVM_CPUID_FLAG_STATEFUL_FUNC;
@@ -544,6 +554,11 @@ int kvm_arch_init_vcpu(CPUState *cs)
if (i == 0xd && c->eax == 0) {
continue;
}
+ if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
+ fprintf(stderr, "cpuid_data is full, no space for "
+ "cpuid(eax:0x%x,ecx:0x%x)\n", i, j);
+ abort();
+ }
c = &cpuid_data.entries[cpuid_i++];
}
break;
@@ -557,6 +572,10 @@ int kvm_arch_init_vcpu(CPUState *cs)
cpu_x86_cpuid(env, 0x80000000, 0, &limit, &unused, &unused, &unused);
for (i = 0x80000000; i <= limit; i++) {
+ if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
+ fprintf(stderr, "unsupported xlevel value: 0x%x\n", limit);
+ abort();
+ }
c = &cpuid_data.entries[cpuid_i++];
c->function = i;
@@ -569,6 +588,10 @@ int kvm_arch_init_vcpu(CPUState *cs)
cpu_x86_cpuid(env, 0xC0000000, 0, &limit, &unused, &unused, &unused);
for (i = 0xC0000000; i <= limit; i++) {
+ if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
+ fprintf(stderr, "unsupported xlevel2 value: 0x%x\n", limit);
+ abort();
+ }
c = &cpuid_data.entries[cpuid_i++];
c->function = i;