[PPP_MPPE]: Don't put InterimKey on the stack

ppp_mppe puts a crypto key on the kernel stack, then passes the
address of that into the crypto layer.  That doesn't work because the
crypto layer needs to be able to do virt_to_*() on the address which
does not universally work for the kernel stack on all platforms.

Adrian Bunk:
Backported to 2.6.16.

Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Adrian Bunk <bunk@kernel.org>

1 files changed, 6 insertions, 8 deletions

diff --git a/drivers/net/ppp_mppe.c b/drivers/net/ppp_mppe.c
index 1985d1b57c45..475093ac98e8 100644
--- a/drivers/net/ppp_mppe.c
+++ b/drivers/net/ppp_mppe.c
@@ -135,7 +135,7 @@ struct ppp_mppe_state {
  * Key Derivation, from RFC 3078, RFC 3079.
  * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
  */
-static void get_new_key_from_sha(struct ppp_mppe_state * state, unsigned char *InterimKey)
+static void get_new_key_from_sha(struct ppp_mppe_state * state)
 {
 	struct scatterlist sg[4];
 
@@ -145,8 +145,6 @@ static void get_new_key_from_sha(struct ppp_mppe_state * state, unsigned char *I
 	setup_sg(&sg[3], sha_pad->sha_pad2, sizeof(sha_pad->sha_pad2));
 
 	crypto_digest_digest (state->sha1, sg, 4, state->sha1_digest);
-
-	memcpy(InterimKey, state->sha1_digest, state->keylen);
 }
 
 /*
@@ -155,20 +153,20 @@ static void get_new_key_from_sha(struct ppp_mppe_state * state, unsigned char *I
  */
 static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
 {
-	unsigned char InterimKey[MPPE_MAX_KEY_LEN];
 	struct scatterlist sg_in[1], sg_out[1];
 
-	get_new_key_from_sha(state, InterimKey);
+	get_new_key_from_sha(state);
 	if (!initial_key) {
-		crypto_cipher_setkey(state->arc4, InterimKey, state->keylen);
-		setup_sg(sg_in, InterimKey, state->keylen);
+		crypto_cipher_setkey(state->arc4, state->sha1_digest,
+					state->keylen);
+		setup_sg(sg_in, state->sha1_digest, state->keylen);
 		setup_sg(sg_out, state->session_key, state->keylen);
 		if (crypto_cipher_encrypt(state->arc4, sg_out, sg_in,
 				      state->keylen) != 0) {
     		    printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n");
 		}
 	} else {
-		memcpy(state->session_key, InterimKey, state->keylen);
+		memcpy(state->session_key, state->sha1_digest, state->keylen);
 	}
 	if (state->keylen == 8) {
 		/* See RFC 3078 */