Resolving the buffer accessed out of bound issue

While packing shared buffer with names of all shared objects present
in custom DSP_LIBRARY_PATH , their is a possibility of buffer overflow
if the shared object names are exceeding the desired limit.The change
makes sure the limit is not exceeded thus avoiding buffer overflow.
Also, the buffer was allocated with 1KB memory which might fall short
to accomodate all the needed shared object names so, increasing this
size to 2KB.

Signed-off-by: Anand Kulkarni <quic_anankulk@quicinc.com>

Author: quic-anankulk

inc/apps_std_internal.h

@@ -19,6 +19,8 @@
 #define ADSP_LIBRARY_PATH "ADSP_LIBRARY_PATH"
 #define DSP_LIBRARY_PATH "DSP_LIBRARY_PATH"
 #define ADSP_AVS_PATH "ADSP_AVS_CFG_PATH"
+#define MAX_NON_PRELOAD_LIBS_LEN 2048
+#define FILE_EXT ".so"
 
 // Locations where shell file can be found
 #ifndef ENABLE_UPSTREAM_DRIVER_INTERFACE

src/fastrpc_procbuf.c

@@ -20,7 +20,6 @@
 
 /* size of buffer used to share the inital config params to dsp */
 #define PROC_SHAREDBUF_SIZE (4*1024)
-#define ENV_PATH_LEN 256
 #define WORD_SIZE 4
 
 extern struct handle_list *hlist;
@@ -69,13 +68,16 @@ int proc_sharedbuf_init(int dev, int domain) {
 
 static int get_non_preload_lib_names (char** lib_names, size_t* buffer_size, int domain)
 {
-	int nErr = AEE_SUCCESS, env_list_len = 0;
+	int nErr = AEE_SUCCESS, env_list_len = 0,  concat_len = 0, new_len = 0;
 	char* data_paths = NULL;
 	char *saveptr       = NULL;
-	VERIFYC(NULL != (data_paths = calloc(1, sizeof(char) * ENV_PATH_LEN)), AEE_ENOMEMORY);
-	VERIFY(AEE_SUCCESS == (nErr = apps_std_getenv(DSP_LIBRARY_PATH, data_paths, ENV_PATH_LEN, &env_list_len)));
+	size_t dsp_search_path_len = std_strlen(DSP_LIBRARY_PATH) + 1;
 
-	char* path = strtok_r(data_paths, ":", &saveptr);
+	VERIFYC(*lib_names != NULL, AEE_ENOMEMORY);
+	VERIFYC(NULL != (data_paths = calloc(1, sizeof(char) * dsp_search_path_len)), AEE_ENOMEMORY);
+	VERIFYC(AEE_SUCCESS == apps_std_getenv(DSP_LIBRARY_PATH, data_paths, dsp_search_path_len, &env_list_len), AEE_EGETENV);
+
+	char* path = strtok_r(data_paths, ";", &saveptr);
 	while (path != NULL)
 	{
 		struct dirent *entry;
@@ -85,23 +87,31 @@ static int get_non_preload_lib_names (char** lib_names, size_t* buffer_size, int
 		while ((entry = readdir(dir)) != NULL) {
 			if ( entry -> d_type == DT_REG) {
 				char* file = entry->d_name;
-				if ( strstr (file, ".so") != NULL) {
-					size_t new_len = *buffer_size + std_strlen(file) + 1;
-					VERIFYC(NULL != (*lib_names = realloc (*lib_names, new_len)), AEE_ENOMEMORY);
-					std_strlcat(*lib_names, file, new_len);
-					std_strlcat(*lib_names, ";", new_len);
-					*buffer_size = new_len;
+				if (std_strstr(file, FILE_EXT) != NULL) {
+					if (concat_len + std_strlen(file) > MAX_NON_PRELOAD_LIBS_LEN) {
+						FARF(ALWAYS,"ERROR: Failed to pack library names in custom DSP_LIBRARY_PATH as required buffer size exceeds Max limit (%d).", MAX_NON_PRELOAD_LIBS_LEN);
+						nErr = AEE_EBUFFERTOOSMALL;
+						closedir(dir);
+						goto bail;
+					}
+					std_strlcat(*lib_names, file, MAX_NON_PRELOAD_LIBS_LEN);
+					concat_len = std_strlcat(*lib_names, ";", MAX_NON_PRELOAD_LIBS_LEN);
 				}
 			}
 		}
-		closedir(dir);
-		path = strtok_r(NULL,":", &saveptr);
+		if (dir != NULL) {
+			closedir(dir);
+		}
+		path = strtok_r(NULL,";", &saveptr);
 	}
-	(*lib_names)[*buffer_size - 1] = '\0';
 	*buffer_size = std_strlen(*lib_names) + 1;
 
 bail:
-	if (nErr) {
+	if (data_paths) {
+		free(data_paths);
+		data_paths = NULL;
+	}
+	if (nErr && (nErr != AEE_EGETENV)) {
 		FARF(ERROR, "Error 0x%x: %s Failed for domain %d (%s)\n",
 					nErr, __func__, domain, strerror(errno));
 	}
@@ -238,14 +248,15 @@ void fastrpc_process_pack_params(int dev, int domain) {
 		FARF(ERROR, "Error 0x%x: %s: Failed to pack effective domain id %d in shared buffer",
 				nErr, __func__, domain);
 	}
-	if (AEE_SUCCESS != get_non_preload_lib_names(&lib_names, &buffer_size, domain)){
-		return;
-	}
-	nErr = pack_proc_shared_buf_params(domain, CUSTOM_DSP_SEARCH_PATH_LIBS_ID,
-			lib_names, buffer_size);
-	if (nErr) {
-		FARF(ERROR, "Error 0x%x: %s: Failed to pack the directory list in shared buffer",
-				nErr, __func__);
+	lib_names = (char *)malloc(sizeof(char) * MAX_NON_PRELOAD_LIBS_LEN);
+	if (lib_names) {
+		if (AEE_SUCCESS == get_non_preload_lib_names(&lib_names, &buffer_size, domain)) {
+			nErr = pack_proc_shared_buf_params(domain, CUSTOM_DSP_SEARCH_PATH_LIBS_ID, lib_names, buffer_size);
+			if (nErr) {
+				FARF(ERROR, "Error 0x%x: %s: Failed to pack the directory list in shared buffer",
+								nErr, __func__);
+			}
+		}
 	}
 	nErr = pack_proc_shared_buf_params(domain, HLOS_PROC_SESS_ID,
 			&sess_id, sizeof(sess_id));