Re: [Xen-devel] [PATCH] tools/ocaml: oxenstored: correctly handle a full ring.

[Keir Fraser <keir@xxxxxxx>]

Who are you looking for an Ack from? The patch makes pefect sense to me so
you can have mine if you want it.

Acked-by: Keir Fraser <keir@xxxxxxx>


On 15/02/2013 08:41, "Ian Campbell" <Ian.Campbell@xxxxxxxxxx> wrote:

> Can I get an ACK or NACK for this please, we really should update XSA-38
> ASAP...
> 
> On Wed, 2013-02-13 at 09:43 +0000, Ian Campbell wrote:
>> Change 26521:2c0fd406f02c (part of XSA-38 / CVE-2013-0215) incorrectly
>> caused us to ignore rather than process a completely full ring. Check if
>> producer and consumer are equal before masking to avoid this, since prod ==
>> cons + PAGE_SIZE after masking becomes prod == cons.
>> 
>> Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
>> ---
>>  tools/ocaml/libs/xb/xs_ring_stubs.c |    4 ++--
>>  1 files changed, 2 insertions(+), 2 deletions(-)
>> 
>> diff --git a/tools/ocaml/libs/xb/xs_ring_stubs.c
>> b/tools/ocaml/libs/xb/xs_ring_stubs.c
>> index 4888ac5..fdd9983 100644
>> --- a/tools/ocaml/libs/xb/xs_ring_stubs.c
>> +++ b/tools/ocaml/libs/xb/xs_ring_stubs.c
>> @@ -45,10 +45,10 @@ static int xs_ring_read(struct mmap_interface *interface,
>> cons = *(volatile uint32*)&intf->req_cons;
>> prod = *(volatile uint32*)&intf->req_prod;
>> xen_mb();
>> - cons = MASK_XENSTORE_IDX(cons);
>> - prod = MASK_XENSTORE_IDX(prod);
>> if (prod == cons)
>> return 0;
>> + cons = MASK_XENSTORE_IDX(cons);
>> + prod = MASK_XENSTORE_IDX(prod);
>> if (prod > cons)
>> to_read = prod - cons;
>> else
> 
> 
> 
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