This is a note to let you know that I've just added the patch titled
xen/io/ring.h: new macro to detect whether there are too many requests on the ring
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
xen-io-ring.h-new-macro-to-detect-whether-there-are-too-many-requests-on-the-ring.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 79c4d036e08cdcd9403047a37cbc9e37b5ee86b4 Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@xxxxxxxx>
Date: Mon, 17 Jun 2013 15:16:33 -0400
Subject: xen/io/ring.h: new macro to detect whether there are too many requests on the ring
From: Jan Beulich <jbeulich@xxxxxxxx>
commit 8d9256906a97c24e97e016482b9be06ea2532b05 upstream.
Backends may need to protect themselves against an insane number of
produced requests stored by a frontend, in case they iterate over
requests until reaching the req_prod value. There can't be more
requests on the ring than the difference between produced requests
and produced (but possibly not yet published) responses.
This is a more strict alternative to a patch previously posted by
Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Yijing Wang <wangyijing@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/xen/interface/io/ring.h | 5 +++++
1 file changed, 5 insertions(+)
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -188,6 +188,11 @@ struct __name##_back_ring { \
#define RING_REQUEST_CONS_OVERFLOW(_r, _cons) \
(((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
+/* Ill-behaved frontend determination: Can there be this many requests? */
+#define RING_REQUEST_PROD_OVERFLOW(_r, _prod) \
+ (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))
+
+
#define RING_PUSH_REQUESTS(_r) do { \
wmb(); /* back sees requests /before/ updated producer index */ \
(_r)->sring->req_prod = (_r)->req_prod_pvt; \
Patches currently in stable-queue which might be from jbeulich@xxxxxxxx are
queue-3.4/xen-events-mask-events-when-changing-their-vcpu-binding.patch
queue-3.4/xen-blkback-check-for-insane-amounts-of-request-on-the-ring-v6.patch
queue-3.4/xen-io-ring.h-new-macro-to-detect-whether-there-are-too-many-requests-on-the-ring.patch
queue-3.4/xen-boot-disable-bios-smp-mp-table-search.patch
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