[PATCH net] af_key: validate families in pfkey_send_migrate()

[Eric Dumazet <edumazet@google.com>]

syzbot was able to trigger a crash in skb_put() [1]

Issue is that pfkey_send_migrate() does not check old/new families,
and that set_ipsecrequest() @family argument was truncated,
thus possibly overfilling the skb.

Validate families early, do not wait set_ipsecrequest().

[1]

skbuff: skb_over_panic: text:ffffffff8a752120 len:392 put:16 head:ffff88802a4ad040 data:ffff88802a4ad040 tail:0x188 end:0x180 dev:<NULL>
 kernel BUG at net/core/skbuff.c:214 !
Call Trace:
 <TASK>
  skb_over_panic net/core/skbuff.c:219 [inline]
  skb_put+0x159/0x210 net/core/skbuff.c:2655
  skb_put_zero include/linux/skbuff.h:2788 [inline]
  set_ipsecrequest net/key/af_key.c:3532 [inline]
  pfkey_send_migrate+0x1270/0x2e50 net/key/af_key.c:3636
  km_migrate+0x155/0x260 net/xfrm/xfrm_state.c:2848
  xfrm_migrate+0x2140/0x2450 net/xfrm/xfrm_policy.c:4705
  xfrm_do_migrate+0x8ff/0xaa0 net/xfrm/xfrm_user.c:3150

Fixes: 08de61beab8a ("[PFKEYV2]: Extension for dynamic update of endpoint address(es)")
Reported-by: syzbot+b518dfc8e021988fbd55@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/69b5933c.050a0220.248e02.00f2.GAE@google.com/T/#u
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
---
 net/key/af_key.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/net/key/af_key.c b/net/key/af_key.c
index 0756bac62f7c042851636badf0a5e961c4e673c1..72ac2ace419de4ae2e4b70c647d8cb2c0781a149 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -3518,7 +3518,7 @@ static int set_sadb_kmaddress(struct sk_buff *skb, const struct xfrm_kmaddress *
 
 static int set_ipsecrequest(struct sk_buff *skb,
 			    uint8_t proto, uint8_t mode, int level,
-			    uint32_t reqid, uint8_t family,
+			    uint32_t reqid, sa_family_t family,
 			    const xfrm_address_t *src, const xfrm_address_t *dst)
 {
 	struct sadb_x_ipsecrequest *rq;
@@ -3583,12 +3583,17 @@ static int pfkey_send_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
 
 	/* ipsecrequests */
 	for (i = 0, mp = m; i < num_bundles; i++, mp++) {
-		/* old locator pair */
-		size_pol += sizeof(struct sadb_x_ipsecrequest) +
-			    pfkey_sockaddr_pair_size(mp->old_family);
-		/* new locator pair */
-		size_pol += sizeof(struct sadb_x_ipsecrequest) +
-			    pfkey_sockaddr_pair_size(mp->new_family);
+		int pair_size;
+
+		pair_size = pfkey_sockaddr_pair_size(mp->old_family);
+		if (!pair_size)
+			return -EINVAL;
+		size_pol += sizeof(struct sadb_x_ipsecrequest) + pair_size;
+
+		pair_size = pfkey_sockaddr_pair_size(mp->new_family);
+		if (!pair_size)
+			return -EINVAL;
+		size_pol += sizeof(struct sadb_x_ipsecrequest) + pair_size;
 	}
 
 	size += sizeof(struct sadb_msg) + size_pol;
-- 
2.53.0.851.ga537e3e6e9-goog