X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lib%2Fringbuffer%2Fring_buffer_backend.c;h=8c9d2b7c54e7b583e896fec159349b2336a0fb21;hb=61eb4c393f32dbea95e9125c6ec4d8cdad535f70;hp=69ad2a709a1d8727862ab1e541438cc616c1f7a3;hpb=5e3912524c2841304e38f962dd8d4cfc6150909e;p=lttng-modules.git

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index 69ad2a70..8c9d2b7c 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);