From 84328342a70a44379dd73011a44c5f5e00481a42 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Fri, 26 Jan 2018 01:36:32 +0200 Subject: [PATCH] ptr_ring: disallow lockless __ptr_ring_full 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 Signed-off-by: David S. Miller --- 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 9a72d8fec50e..f17584680b79 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) { -- 2.20.1