Subject: Re: [PATCH] powerpc/kvm: Handle the boundary condition correctly

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Fri, 23 Aug 2013 09:01:41 +0530

Alexander Graf <[email-masked]> writes:

> On 22.08.2013, at 12:37, Aneesh Kumar K.V wrote:
>
>> From: "Aneesh Kumar K.V" <[email-masked]>
>
> Isn't this you?

Yes. The patches are generated using git format-patch and sent by
git send-email. That's how it always created patches for me. I am not sure if
there is a config I can change to avoid having From:

>
>> 
>> We should be able to copy upto count bytes
>
> Why?
>

Without this we end up doing

 +    struct kvm_get_htab_buf {
 +        struct kvm_get_htab_header header;
 +        /*
 +         * Older kernel required one extra byte.
 +         */
 +        unsigned long hpte[3];
 +    } hpte_buf;

even though we are only looking for one hpte entry.

http://mid.gmane.org/[email-masked]

>
> Alex
>
>> 
>> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
>> ---
>> arch/powerpc/kvm/book3s_64_mmu_hv.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
>> index 710d313..0ae6bb6 100644
>> --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
>> +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
>> @@ -1362,7 +1362,7 @@ static ssize_t kvm_htab_read(struct file *file, char __user *buf,
>> 	lbuf = (unsigned long __user *)buf;
>> 
>> 	nb = 0;
>> -	while (nb + sizeof(hdr) + HPTE_SIZE < count) {
>> +	while (nb + sizeof(hdr) + HPTE_SIZE <= count) {
>> 		/* Initialize header */
>> 		hptr = (struct kvm_get_htab_header __user *)buf;
>> 		hdr.n_valid = 0;
>> @@ -1385,7 +1385,7 @@ static ssize_t kvm_htab_read(struct file *file, char __user *buf,
>> 		/* Grab a series of valid entries */
>> 		while (i < kvm->arch.hpt_npte &&
>> 		       hdr.n_valid < 0xffff &&
>> -		       nb + HPTE_SIZE < count &&
>> +		       nb + HPTE_SIZE <= count &&
>> 		       record_hpte(flags, hptp, hpte, revp, 1, first_pass)) {
>> 			/* valid entry, write it out */
>> 			++hdr.n_valid;
>> -- 
>> 1.8.1.2
>>