[Fix] Fix reading of the cached maps

Issue: #4213

diff --git a/src/libserver/maps/map.c b/src/libserver/maps/map.c
index 995509dedc845beae495b5a70c9d41f017c2de97..f9933cee6599d3445c7438d873015cf561e1b739 100644 (file)
--- a/src/libserver/maps/map.c
+++ b/src/libserver/maps/map.c
@@ -1319,13 +1319,13 @@ static gboolean
 rspamd_map_read_cached (struct rspamd_map *map, struct rspamd_map_backend *bk,
                struct map_periodic_cbdata *periodic, const gchar *host)
 {
-       gsize len;
+       gsize mmap_len, len;
        gpointer in;
        struct http_map_data *data;
 
        data = bk->data.hd;
 
-       in = rspamd_shmem_xmap (data->cache->shmem_name, PROT_READ, &len);
+       in = rspamd_shmem_xmap (data->cache->shmem_name, PROT_READ, &mmap_len);
 
        if (in == NULL) {
                msg_err ("cannot map cache from %s: %s", data->cache->shmem_name,
@@ -1333,15 +1333,24 @@ rspamd_map_read_cached (struct rspamd_map *map, struct rspamd_map_backend *bk,
                return FALSE;
        }
 
-       if (len < data->cache->len) {
-               msg_err ("cannot map cache from %s: bad length %z, %z expected",
+       if (mmap_len < data->cache->len) {
+               msg_err ("cannot map cache from %s: truncated length %z, %z expected",
                                data->cache->shmem_name,
-                               len, data->cache->len);
-               munmap (in, len);
+                               mmap_len, data->cache->len);
+               munmap (in, mmap_len);
 
                return FALSE;
        }
 
+       /*
+        * Len is taken from the shmem file size that can be larger than the
+        * actual data length, as we use shared memory as a growing buffer for the
+        * HTTP input.
+        * Hence, we need to use len from the saved cache data, counting that it is
+        * at least not more than the cached file length (this is checked above).
+        */
+       len = data->cache->len;
+
        if (bk->is_compressed) {
                ZSTD_DStream *zstream;
                ZSTD_inBuffer zin;
@@ -1375,7 +1384,7 @@ rspamd_map_read_cached (struct rspamd_map *map, struct rspamd_map_backend *bk,
                                                ZSTD_getErrorName (r));
                                ZSTD_freeDStream (zstream);
                                g_free (out);
-                               munmap (in, len);
+                               munmap (in, mmap_len);
                                return FALSE;
                        }
 
@@ -1395,12 +1404,11 @@ rspamd_map_read_cached (struct rspamd_map *map, struct rspamd_map_backend *bk,
                g_free (out);
        }
        else {
-               msg_info_map ("%s: read map data cached %z bytes", bk->uri,
-                               len);
+               msg_info_map ("%s: read map data cached %z bytes", bk->uri, len);
                map->read_callback (in, len, &periodic->cbdata, TRUE);
        }
 
-       munmap (in, len);
+       munmap (in, mmap_len);
 
        return TRUE;
 }