Messages in this thread | | | Date | Tue, 10 Jan 2023 11:16:30 -0600 | Subject | Re: [PATCH] KVM: sev: Fix int overflow in send|recieve_update_data ioctls | From | Tom Lendacky <> |
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On 1/10/23 10:44, Peter Gonda wrote: >>> >>> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >>> index 273cba809328..9451de72f917 100644 >>> --- a/arch/x86/kvm/svm/sev.c >>> +++ b/arch/x86/kvm/svm/sev.c >>> @@ -1294,7 +1294,7 @@ static int sev_send_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp) >>> >>> /* Check if we are crossing the page boundary */ >>> offset = params.guest_uaddr & (PAGE_SIZE - 1); >>> - if ((params.guest_len + offset > PAGE_SIZE)) >>> + if (params.guest_len > PAGE_SIZE || (params.guest_len + offset > PAGE_SIZE)) >> >> I see the original if statement had double parentheses, which looks >> strange. Should this if (and the one below) be: >> >> if (params.guest_len > PAGE_SIZE || (params.guest_len + offset) > PAGE_SIZE) > > Isn't the order of operations here: '+' and then '>'. So is the patch > correct and matches the old conditional? I am fine adding additional
But what was the purpose of them in the old conditional? They weren't necessary.
But, yes, that order of operations is correct and those are both before '||'. So the extra parentheses around the second condition check are still strange then, right?
Given that, then:
if (params.guest_len > PAGE_SIZE || params.guest_len + offset > PAGE_SIZE)
> () for clarity though.
I do like the look and clarity of the parentheses around the addition.
Thanks, Tom
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