From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: [PATCH net-next 05/12] ptr_ring: disallow lockless __ptr_ring_full Date: Fri, 26 Jan 2018 01:36:32 +0200 Message-ID: <1516923320-16959-6-git-send-email-mst@redhat.com> References: <1516923320-16959-1-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org, Jason Wang , John Fastabend , David Miller To: linux-kernel@vger.kernel.org Return-path: Content-Disposition: inline In-Reply-To: <1516923320-16959-1-git-send-email-mst@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Similar to bcecb4bbf88a ("net: ptr_ring: otherwise safe empty checks can overrun array bounds") a lockless use of __ptr_ring_full might cause an out of bounds access. We can fix this, but it's easier to just disallow lockless __ptr_ring_full for now. Signed-off-by: Michael S. Tsirkin --- include/linux/ptr_ring.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/include/linux/ptr_ring.h b/include/linux/ptr_ring.h index 9a72d8f..f175846 100644 --- a/include/linux/ptr_ring.h +++ b/include/linux/ptr_ring.h @@ -45,9 +45,10 @@ struct ptr_ring { }; /* Note: callers invoking this in a loop must use a compiler barrier, - * for example cpu_relax(). If ring is ever resized, callers must hold - * producer_lock - see e.g. ptr_ring_full. Otherwise, if callers don't hold - * producer_lock, the next call to __ptr_ring_produce may fail. + * for example cpu_relax(). + * + * NB: this is unlike __ptr_ring_empty in that callers must hold producer_lock: + * see e.g. ptr_ring_full. */ static inline bool __ptr_ring_full(struct ptr_ring *r) { -- MST