rpc-sys: packagelist: check calloc() result for world array

rpc_sys_packagelist() allocated the "world" pointer array with calloc()
and immediately dereferenced it ("world[0] = world_mmap") without
checking for allocation failure.  Under memory pressure this would
dereference a NULL pointer and crash the daemon.

Bail out with UBUS_STATUS_UNKNOWN_ERROR on allocation failure, releasing
the mmap and the open status file first.

Assisted-by: Claude:claude-opus-4-8
Link: https://github.com/openwrt/rpcd/pull/34
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

1 files changed, 5 insertions, 0 deletions

diff --git a/sys.c b/sys.c
index 7676ba6..5e1cc18 100644
--- a/sys.c
+++ b/sys.c
@@ -280,6 +280,11 @@ rpc_sys_packagelist(struct ubus_context *ctx, struct ubus_object *obj,
 		if (nstrs) {
 			/* extra one in world for NULL sentinel */
 			world = (const char **)calloc(nstrs+1, sizeof(char *));
+			if (!world) {
+				munmap(world_mmap, world_mmap_size);
+				fclose(f);
+				return UBUS_STATUS_UNKNOWN_ERROR;
+			}
 			world[0] = world_mmap;
 			for (istr = 1, s = world_mmap; *s; s++) {
 				if (*s == '\n') {