Initialize pad memory to pacify stack protectors

[pam_pcsc_cr.git] / authobj.c

diff --git a/authobj.c b/authobj.c
index b402094df224cd13651227c15e47bb9184976343..deba02868152e70a575194b452ac828d1d1e903f 100644 (file)
--- a/authobj.c
+++ b/authobj.c
@@ -126,6 +126,15 @@ make_authobj(const char *userid, const char *password, const char *nonce,
        datasize = ((secsize + paylsize + HASHSIZE + 4 * sizeof(short) - 1) /
                        CBLKSIZE + 1) * CBLKSIZE;
        data = alloca(datasize);
+       /* 
+          We allocate memory rounded up to CBLKSIZE on the stack, but do not
+          use the last bytes. Stack protectors, if enabled, fill this memory
+          with `canary` value. Later, when encryption function is called,
+          stack protector detects that it tries to access "uninitialized
+          memory". Which, while technically true, is not an error. Still,
+          let us make stack protector happy by initializing the whole area:
+        */
+       memset(data, 0, datasize);
        serial_init(&srl, data, datasize);
        if (serial_put(&srl, secret, secsize) != secsize) {
                ao.err = "authobj: serialization of secret failed";