On 2018年01月26日 07:36, Michael S. Tsirkin wrote:
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.
It looks to me that just fix this is better than disallow through doc
(which is easily to be ignored ...).
Thanks
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
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)
{
