From: Juergen Gross Date: Mon, 17 May 2021 13:43:04 +0000 (+0200) Subject: include/public: add RING_RESPONSE_PROD_OVERFLOW macro X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~42^2~516 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=d1f6296053f464c9da6f6fa5f1ece864130718ce;p=xen.git include/public: add RING_RESPONSE_PROD_OVERFLOW macro Add a new RING_RESPONSE_PROD_OVERFLOW() macro for being able to detect an ill-behaved backend tampering with the response producer index. Signed-off-by: Juergen Gross Acked-by: Jan Beulich --- diff --git a/xen/include/public/io/ring.h b/xen/include/public/io/ring.h index 0b08b2697e..c486c457e0 100644 --- a/xen/include/public/io/ring.h +++ b/xen/include/public/io/ring.h @@ -259,6 +259,10 @@ typedef struct __name##_back_ring __name##_back_ring_t #define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \ (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r)) +/* Ill-behaved backend determination: Can there be this many responses? */ +#define RING_RESPONSE_PROD_OVERFLOW(_r, _prod) \ + (((_prod) - (_r)->rsp_cons) > RING_SIZE(_r)) + #define RING_PUSH_REQUESTS(_r) do { \ xen_wmb(); /* back sees requests /before/ updated producer index */ \ (_r)->sring->req_prod = (_r)->req_prod_pvt; \