From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Sat, 20 Aug 2011 13:43:48 +0000 (-0400)
Subject: comment shm
X-Git-Tag: v1.9.1~294
X-Git-Url: http://git.liburcu.org/?a=commitdiff_plain;h=ed5426d36fe2da648b4b16ec8173398558d8490f;p=lttng-ust.git

comment shm

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/libringbuffer/shm.h b/libringbuffer/shm.h
index 9f72a5a2..22c9afdc 100644
--- a/libringbuffer/shm.h
+++ b/libringbuffer/shm.h
@@ -17,6 +17,11 @@
 /*
  * Pointer dereferencing. We don't trust the shm_ref, so we validate
  * both the index and offset with known boundaries.
+ *
+ * "shmp" and "shmp_index" guarantee that it's safe to use the pointer
+ * target type, even in the occurrence of shm_ref modification by an
+ * untrusted process having write access to the shm_ref. We return a
+ * NULL pointer if the ranges are invalid.
  */
 static inline
 char *_shmp_offset(struct shm_object_table *table, struct shm_ref *ref,