leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity

KVM: x86: avoid vmalloc(0) in the KVM_SET_CPUID

Browse Source 
This causes an ugly dmesg splat.  Beautified syzkaller testcase:

    #include <unistd.h>
    #include <sys/syscall.h>
    #include <sys/ioctl.h>
    #include <fcntl.h>
    #include <linux/kvm.h>

    long r[8];

    int main()
    {
        struct kvm_cpuid2 c = { 0 };
        r[2] = open("/dev/kvm", O_RDWR);
        r[3] = ioctl(r[2], KVM_CREATE_VM, 0);
        r[4] = ioctl(r[3], KVM_CREATE_VCPU, 0x8);
        r[7] = ioctl(r[4], KVM_SET_CPUID, &c);
        return 0;
    }

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
This commit is contained in:
Paolo Bonzini 2016-06-01 14:09:19 +02:00 committed by Radim Krčmář
parent b21629da12
commit 83676e9238
1 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
arch/x86/kvm/cpuid.c
View File

@ -181,19 +181,22 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
struct kvm_cpuid_entry __user *entries)
{
int r, i;
struct kvm_cpuid_entry *cpuid_entries;
struct kvm_cpuid_entry *cpuid_entries = NULL;
r = -E2BIG;
if (cpuid->nent > KVM_MAX_CPUID_ENTRIES)
goto out;
r = -ENOMEM;
cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) * cpuid->nent);
if (!cpuid_entries)
goto out;
r = -EFAULT;
if (copy_from_user(cpuid_entries, entries,
cpuid->nent * sizeof(struct kvm_cpuid_entry)))
goto out_free;
if (cpuid->nent) {
cpuid_entries = vmalloc(sizeof(struct kvm_cpuid_entry) *
cpuid->nent);
if (!cpuid_entries)
goto out;
r = -EFAULT;
if (copy_from_user(cpuid_entries, entries,
cpuid->nent * sizeof(struct kvm_cpuid_entry)))
goto out;
}
for (i = 0; i < cpuid->nent; i++) {
vcpu->arch.cpuid_entries[i].function = cpuid_entries[i].function;
vcpu->arch.cpuid_entries[i].eax = cpuid_entries[i].eax;
@ -212,9 +215,8 @@ int kvm_vcpu_ioctl_set_cpuid(struct kvm_vcpu *vcpu,
kvm_x86_ops->cpuid_update(vcpu);
r = kvm_update_cpuid(vcpu);
out_free:
vfree(cpuid_entries);
out:
vfree(cpuid_entries);
return r;
}