file: avoid sending uninitialized stack memory for broken symlinks

When readlink() fails (returns -1), tbuf is left uninitialized.
The unconditional blobmsg_add_string() call that followed would
include whatever happened to be on the stack in the RPC reply,
leaking kernel/stack memory to callers.

Only add the "name" field to the response when readlink() succeeds.

Assisted-by: Claude:claude-sonnet-4-6
Link: https://github.com/openwrt/rpcd/pull/34
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/file.c b/file.c
index eeb0713..fd4925c 100644
--- a/file.c
+++ b/file.c
@@ -579,8 +579,8 @@ rpc_file_list(struct ubus_context *ctx, struct ubus_object *obj,
 				tlen = readlink(entrypath, tbuf, sizeof(tbuf) - 1);
 				if (tlen >= 0) {
 					tbuf[tlen] = '\0';
+					blobmsg_add_string(&buf, "name", tbuf);
 				}
-				blobmsg_add_string(&buf, "name", tbuf);
 
 				struct stat target;
 				if (!stat(entrypath, &target)) {