[PATCH 10/36] cmd/libsnap-confine-private: Fix use of uninitialised variable

Ensure xdg_runtime_dir_env is zero initialisd in
sc_call_snap_update_ns_as_user() otherwise when XDG_RUNTIME_DIR is not
defined the uninitialised contents of this buffer will be passed to
snap-update-ns. This is unlikely to be an issue in practice as
snap-update-ns is quite defensive in terms of environment variable handing
already.

Signed-off-by: Alex Murray <alex.murray@canonical.com>
Gbp-Pq: Topic cve202144730
Gbp-Pq: Name 0010-cmd-libsnap-confine-private-Fix-use-of-uninitialised.patch

diff --git a/cmd/libsnap-confine-private/tool.c b/cmd/libsnap-confine-private/tool.c
index fc67ebb2447e49ab5fa6b4db551d9eb6f2aa797f..36666df919f17be92f8d96efd77b900fbd1d6bfc 100644 (file)
--- a/cmd/libsnap-confine-private/tool.c
+++ b/cmd/libsnap-confine-private/tool.c
@@ -105,7 +105,7 @@ void sc_call_snap_update_ns_as_user(int snap_update_ns_fd,
                         snap_name);
 
        const char *xdg_runtime_dir = getenv("XDG_RUNTIME_DIR");
-       char xdg_runtime_dir_env[PATH_MAX+strlen("XDG_RUNTIME_DIR=")];
+       char xdg_runtime_dir_env[PATH_MAX+sizeof("XDG_RUNTIME_DIR=")] = { 0 };
        if (xdg_runtime_dir != NULL) {
                sc_must_snprintf(xdg_runtime_dir_env,
                                 sizeof(xdg_runtime_dir_env),