X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fring_buffer_backend.c;fp=lib%2Fringbuffer%2Fring_buffer_backend.c;h=f846c7d9b5a268d01d8f66b27aa14282dd2a1064;hb=ee14661309be11bfacde9a92c0546dcc395d8e1f;hp=84e7dfb715c6ea1453478f6f85cd5dc8df54170c;hpb=18a74f1712ea052f0cdfb75c5b2d64bffc4e2f5a;p=lttng-modules.git

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index 84e7dfb7..f846c7d9 100644
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -724,8 +724,9 @@ EXPORT_SYMBOL_GPL(__lib_ring_buffer_copy_to_user);
  * @dest : destination address
  * @len : destination's length
  *
- * return string's length
+ * Return string's length, or -EINVAL on error.
  * Should be protected by get_subbuf/put_subbuf.
+ * Destination length should be at least 1 to hold '\0'.
  */
 int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offset,
 			      void *dest, size_t len)
@@ -741,6 +742,8 @@ int lib_ring_buffer_read_cstr(struct lib_ring_buffer_backend *bufb, size_t offse
 	offset &= chanb->buf_size - 1;
 	index = (offset & (chanb->subbuf_size - 1)) >> PAGE_SHIFT;
 	orig_offset = offset;
+	if (unlikely(!len))
+		return -EINVAL;
 	for (;;) {
 		id = bufb->buf_rsb.id;
 		sb_bindex = subbuffer_id_get_index(config, id);