Fix: sysconf() unchecked return value

[lttng-ust.git] / libringbuffer / ring_buffer_backend.c

diff --git a/libringbuffer/ring_buffer_backend.c b/libringbuffer/ring_buffer_backend.c
index 7d3a37809e73da27b25d43d8914ed285545075f7..6d2d9507bec59edfe56658a0c8e10efffaf8d132 100644 (file)
--- a/libringbuffer/ring_buffer_backend.c
+++ b/libringbuffer/ring_buffer_backend.c
@@ -19,6 +19,7 @@
  */
 
 #define _GNU_SOURCE
+#include <unistd.h>
 #include <urcu/arch.h>
 #include <limits.h>
 
@@ -49,6 +50,7 @@ int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_conf
        unsigned long subbuf_size, mmap_offset = 0;
        unsigned long num_subbuf_alloc;
        unsigned long i;
+       long page_size;
 
        subbuf_size = chanb->subbuf_size;
        num_subbuf_alloc = num_subbuf;
@@ -56,6 +58,11 @@ int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_conf
        if (extra_reader_sb)
                num_subbuf_alloc++;
 
+       page_size = sysconf(_SC_PAGE_SIZE);
+       if (page_size <= 0) {
+               goto page_size_error;
+       }
+
        align_shm(shmobj, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
        set_shmp(bufb->array, zalloc_shm(shmobj,
                        sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc));
@@ -64,9 +71,9 @@ int lib_ring_buffer_backend_allocate(const struct lttng_ust_lib_ring_buffer_conf
 
        /*
         * This is the largest element (the buffer pages) which needs to
-        * be aligned on PAGE_SIZE.
+        * be aligned on page size.
         */
-       align_shm(shmobj, PAGE_SIZE);
+       align_shm(shmobj, page_size);
        set_shmp(bufb->memory_map, zalloc_shm(shmobj,
                        subbuf_size * num_subbuf_alloc));
        if (caa_unlikely(!shmp(handle, bufb->memory_map)))
@@ -123,6 +130,7 @@ free_array:
 memory_map_error:
        /* bufb->array will be freed by shm teardown */
 array_error:
+page_size_error:
        return -ENOMEM;
 }
 
@@ -196,7 +204,7 @@ void channel_backend_reset(struct channel_backend *chanb)
  * @name: channel name
  * @config: client ring buffer configuration
  * @parent: dentry of parent directory, %NULL for root directory
- * @subbuf_size: size of sub-buffers (> PAGE_SIZE, power of 2)
+ * @subbuf_size: size of sub-buffers (> page size, power of 2)
  * @num_subbuf: number of sub-buffers (power of 2)
  * @lttng_ust_shm_handle: shared memory handle
  *
@@ -218,12 +226,17 @@ int channel_backend_init(struct channel_backend *chanb,
        unsigned int i;
        int ret;
        size_t shmsize = 0, num_subbuf_alloc;
+       long page_size;
 
        if (!name)
                return -EPERM;
 
+       page_size = sysconf(_SC_PAGE_SIZE);
+       if (page_size <= 0) {
+               return -ENOMEM;
+       }
        /* Check that the subbuffer size is larger than a page. */
-       if (subbuf_size < PAGE_SIZE)
+       if (subbuf_size < page_size)
                return -EINVAL;
 
        /*
@@ -266,7 +279,7 @@ int channel_backend_init(struct channel_backend *chanb,
        num_subbuf_alloc = num_subbuf + 1;
        shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages_shmp));
        shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages_shmp) * num_subbuf_alloc;
-       shmsize += offset_align(shmsize, PAGE_SIZE);
+       shmsize += offset_align(shmsize, page_size);
        shmsize += subbuf_size * num_subbuf_alloc;
        shmsize += offset_align(shmsize, __alignof__(struct lttng_ust_lib_ring_buffer_backend_pages));
        shmsize += sizeof(struct lttng_ust_lib_ring_buffer_backend_pages) * num_subbuf_alloc;