llext: fix memory leak in no-data case

If there is no .data section in a llext module, the base data address is
replaced with the .bss address while loading the module. There is no a
corresponding logic during module unloading. This causes a memory leak
because FW attempts to free memory under a NULL address while the .bss
memory remains allocated. This change adds the missing logic.

Signed-off-by: Wojciech Jablonski <wojciech.jablonski@intel.com>

Author: wjablon1

src/library_manager/llext_manager.c

@@ -320,6 +320,8 @@ static int llext_manager_unload_module(struct lib_manager_module *mctx)
 	/* Writable data (.data, .bss, etc.) */
 	void __sparse_cache *va_base_data = (void __sparse_cache *)
 		mctx->segment[LIB_MANAGER_DATA].addr;
+	void __sparse_cache *va_base_bss = (void __sparse_cache *)
+		mctx->segment[LIB_MANAGER_BSS].addr;
 	size_t data_size = mctx->segment[LIB_MANAGER_DATA].size +
 		mctx->segment[LIB_MANAGER_BSS].size;
 	int err = 0, ret;
@@ -330,6 +332,12 @@ static int llext_manager_unload_module(struct lib_manager_module *mctx)
 	if (ret < 0)
 		err = ret;
 
+	/* Mimic the logic from load_module where the .bss address is used for mapping
+	 * in case of e.g. lack of writable .data section
+	 */
+	if (!va_base_data)
+		va_base_data = va_base_bss;
+
 	llext_manager_unmap_detached_sections(ldr, ext, LLEXT_MEM_DATA,
 					      va_base_data, data_size);
 	ret = llext_manager_align_unmap(va_base_data, data_size);