Fix: ensure userspace accesses are done with _inatomic

[lttng-modules.git] / lib / ringbuffer / ring_buffer_backend.c

diff --git a/lib/ringbuffer/ring_buffer_backend.c b/lib/ringbuffer/ring_buffer_backend.c
index 11dd924ed4e6a90fe208c0eafb0c7ae0523431e4..84e7dfb715c6ea1453478f6f85cd5dc8df54170c 100644 (file)
--- a/lib/ringbuffer/ring_buffer_backend.c
+++ b/lib/ringbuffer/ring_buffer_backend.c
@@ -1,9 +1,21 @@
 /*
  * ring_buffer_backend.c
  *
- * Copyright (C) 2005-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * Copyright (C) 2005-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  *
- * Dual LGPL v2.1/GPL v2 license.
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include <linux/stddef.h>
@@ -307,18 +319,18 @@ int channel_backend_init(struct channel_backend *chanb,
        if (!name)
                return -EPERM;
 
-       if (!(subbuf_size && num_subbuf))
-               return -EPERM;
-
        /* Check that the subbuffer size is larger than a page. */
        if (subbuf_size < PAGE_SIZE)
                return -EINVAL;
 
        /*
-        * Make sure the number of subbuffers and subbuffer size are power of 2.
+        * Make sure the number of subbuffers and subbuffer size are
+        * power of 2 and nonzero.
         */
-       CHAN_WARN_ON(chanb, hweight32(subbuf_size) != 1);
-       CHAN_WARN_ON(chanb, hweight32(num_subbuf) != 1);
+       if (!subbuf_size || (subbuf_size & (subbuf_size - 1)))
+               return -EINVAL;
+       if (!num_subbuf || (num_subbuf & (num_subbuf - 1)))
+               return -EINVAL;
 
        ret = subbuffer_id_check_index(config, num_subbuf);
        if (ret)
@@ -547,7 +559,7 @@ EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset);
 
 
 /**
- * lib_ring_buffer_copy_from_user - write user data to a ring_buffer buffer.
+ * lib_ring_buffer_copy_from_user_inatomic - write user data to a ring_buffer buffer.
  * @bufb : buffer backend
  * @offset : offset within the buffer
  * @src : source address
@@ -558,7 +570,7 @@ EXPORT_SYMBOL_GPL(_lib_ring_buffer_memset);
  * directly without having the src pointer checked with access_ok()
  * previously.
  */
-void _lib_ring_buffer_copy_from_user(struct lib_ring_buffer_backend *bufb,
+void _lib_ring_buffer_copy_from_user_inatomic(struct lib_ring_buffer_backend *bufb,
                                      size_t offset,
                                      const void __user *src, size_t len,
                                      ssize_t pagecpy)
@@ -589,7 +601,7 @@ void _lib_ring_buffer_copy_from_user(struct lib_ring_buffer_backend *bufb,
                rpages = bufb->array[sb_bindex];
                CHAN_WARN_ON(chanb, config->mode == RING_BUFFER_OVERWRITE
                                && subbuffer_id_is_noref(config, id));
-               ret = lib_ring_buffer_do_copy_from_user(rpages->p[index].virt
+               ret = lib_ring_buffer_do_copy_from_user_inatomic(rpages->p[index].virt
                                                        + (offset & ~PAGE_MASK),
                                                        src, pagecpy) != 0;
                if (ret > 0) {
@@ -600,7 +612,7 @@ void _lib_ring_buffer_copy_from_user(struct lib_ring_buffer_backend *bufb,
                }
        } while (unlikely(len != pagecpy));
 }
-EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user);
+EXPORT_SYMBOL_GPL(_lib_ring_buffer_copy_from_user_inatomic);
 
 /**
  * lib_ring_buffer_read - read data from ring_buffer_buffer.