Fix: don't dereference NULL pointers

[lttng-ust.git] / liblttng-ust-ctl / ustctl.c

diff --git a/liblttng-ust-ctl/ustctl.c b/liblttng-ust-ctl/ustctl.c
index b44d9e34020a5cbe61d547c4b8ba7d01e723bc83..90e3094e8d12359d1ad5f0d07f49c8c9dd37e923 100644 (file)
--- a/liblttng-ust-ctl/ustctl.c
+++ b/liblttng-ust-ctl/ustctl.c
@@ -1334,6 +1334,8 @@ int ustctl_get_mmap_read_offset(struct ustctl_consumer_stream *stream,
        unsigned long sb_bindex;
        struct lttng_ust_lib_ring_buffer *buf;
        struct ustctl_consumer_channel *consumer_chan;
+       struct lttng_ust_lib_ring_buffer_backend_pages_shmp *barray_idx;
+       struct lttng_ust_lib_ring_buffer_backend_pages *pages;
 
        if (!stream)
                return -EINVAL;
@@ -1344,8 +1346,14 @@ int ustctl_get_mmap_read_offset(struct ustctl_consumer_stream *stream,
                return -EINVAL;
        sb_bindex = subbuffer_id_get_index(&chan->backend.config,
                                        buf->backend.buf_rsb.id);
-       *off = shmp(consumer_chan->chan->handle,
-               shmp_index(consumer_chan->chan->handle, buf->backend.array, sb_bindex)->shmp)->mmap_offset;
+       barray_idx = shmp_index(consumer_chan->chan->handle, buf->backend.array,
+                       sb_bindex);
+       if (!barray_idx)
+               return -EINVAL;
+       pages = shmp(consumer_chan->chan->handle, barray_idx->shmp);
+       if (!pages)
+               return -EINVAL;
+       *off = pages->mmap_offset;
        return 0;
 }
 
@@ -1511,6 +1519,8 @@ struct lttng_ust_client_lib_ring_buffer_client_cb *get_client_cb(
        struct lttng_ust_client_lib_ring_buffer_client_cb *client_cb;
 
        chan = shmp(handle, buf->backend.chan);
+       if (!chan)
+               return NULL;
        config = &chan->backend.config;
        if (!config->cb_ptr)
                return NULL;