diff options
Diffstat (limited to 'arch/powerpc/kvm/book3s_rtas.c')
| -rw-r--r-- | arch/powerpc/kvm/book3s_rtas.c | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/arch/powerpc/kvm/book3s_rtas.c b/arch/powerpc/kvm/book3s_rtas.c index c5e677508d3b..0f847f1e5ddd 100644 --- a/arch/powerpc/kvm/book3s_rtas.c +++ b/arch/powerpc/kvm/book3s_rtas.c @@ -242,6 +242,17 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) * value so we can restore it on the way out. */ orig_rets = args.rets; + if (be32_to_cpu(args.nargs) >= ARRAY_SIZE(args.args)) { + /* + * Don't overflow our args array: ensure there is room for + * at least rets[0] (even if the call specifies 0 nret). + * + * Each handler must then check for the correct nargs and nret + * values, but they may always return failure in rets[0]. + */ + rc = -EINVAL; + goto fail; + } args.rets = &args.args[be32_to_cpu(args.nargs)]; mutex_lock(&vcpu->kvm->arch.rtas_token_lock); @@ -269,9 +280,17 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) fail: /* * We only get here if the guest has called RTAS with a bogus - * args pointer. That means we can't get to the args, and so we - * can't fail the RTAS call. So fail right out to userspace, - * which should kill the guest. + * args pointer or nargs/nret values that would overflow the + * array. That means we can't get to the args, and so we can't + * fail the RTAS call. So fail right out to userspace, which + * should kill the guest. + * + * SLOF should actually pass the hcall return value from the + * rtas handler call in r3, so enter_rtas could be modified to + * return a failure indication in r3 and we could return such + * errors to the guest rather than failing to host userspace. + * However old guests that don't test for failure could then + * continue silently after errors, so for now we won't do this. */ return rc; } |