--- /dev/null
+From 4b66af2d6356a00e94bcdea3e7fea324e8b5c6f4 Mon Sep 17 00:00:00 2001
+From: Kevin Easton <kevin@guarana.org>
+Date: Sat, 7 Apr 2018 11:40:33 -0400
+Subject: af_key: Always verify length of provided sadb_key
+
+From: Kevin Easton <kevin@guarana.org>
+
+commit 4b66af2d6356a00e94bcdea3e7fea324e8b5c6f4 upstream.
+
+Key extensions (struct sadb_key) include a user-specified number of key
+bits. The kernel uses that number to determine how much key data to copy
+out of the message in pfkey_msg2xfrm_state().
+
+The length of the sadb_key message must be verified to be long enough,
+even in the case of SADB_X_AALG_NULL. Furthermore, the sadb_key_len value
+must be long enough to include both the key data and the struct sadb_key
+itself.
+
+Introduce a helper function verify_key_len(), and call it from
+parse_exthdrs() where other exthdr types are similarly checked for
+correctness.
+
+Signed-off-by: Kevin Easton <kevin@guarana.org>
+Reported-by: syzbot+5022a34ca5a3d49b84223653fab632dfb7b4cf37@syzkaller.appspotmail.com
+Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
+Cc: Zubin Mithra <zsm@chromium.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ net/key/af_key.c | 45 +++++++++++++++++++++++++++++++++++----------
+ 1 file changed, 35 insertions(+), 10 deletions(-)
+
+--- a/net/key/af_key.c
++++ b/net/key/af_key.c
+@@ -437,6 +437,24 @@ static int verify_address_len(const void
+ return 0;
+ }
+
++static inline int sadb_key_len(const struct sadb_key *key)
++{
++ int key_bytes = DIV_ROUND_UP(key->sadb_key_bits, 8);
++
++ return DIV_ROUND_UP(sizeof(struct sadb_key) + key_bytes,
++ sizeof(uint64_t));
++}
++
++static int verify_key_len(const void *p)
++{
++ const struct sadb_key *key = p;
++
++ if (sadb_key_len(key) > key->sadb_key_len)
++ return -EINVAL;
++
++ return 0;
++}
++
+ static inline int pfkey_sec_ctx_len(const struct sadb_x_sec_ctx *sec_ctx)
+ {
+ return DIV_ROUND_UP(sizeof(struct sadb_x_sec_ctx) +
+@@ -533,16 +551,25 @@ static int parse_exthdrs(struct sk_buff
+ return -EINVAL;
+ if (ext_hdrs[ext_type-1] != NULL)
+ return -EINVAL;
+- if (ext_type == SADB_EXT_ADDRESS_SRC ||
+- ext_type == SADB_EXT_ADDRESS_DST ||
+- ext_type == SADB_EXT_ADDRESS_PROXY ||
+- ext_type == SADB_X_EXT_NAT_T_OA) {
++ switch (ext_type) {
++ case SADB_EXT_ADDRESS_SRC:
++ case SADB_EXT_ADDRESS_DST:
++ case SADB_EXT_ADDRESS_PROXY:
++ case SADB_X_EXT_NAT_T_OA:
+ if (verify_address_len(p))
+ return -EINVAL;
+- }
+- if (ext_type == SADB_X_EXT_SEC_CTX) {
++ break;
++ case SADB_X_EXT_SEC_CTX:
+ if (verify_sec_ctx_len(p))
+ return -EINVAL;
++ break;
++ case SADB_EXT_KEY_AUTH:
++ case SADB_EXT_KEY_ENCRYPT:
++ if (verify_key_len(p))
++ return -EINVAL;
++ break;
++ default:
++ break;
+ }
+ ext_hdrs[ext_type-1] = (void *) p;
+ }
+@@ -1104,14 +1131,12 @@ static struct xfrm_state * pfkey_msg2xfr
+ key = ext_hdrs[SADB_EXT_KEY_AUTH - 1];
+ if (key != NULL &&
+ sa->sadb_sa_auth != SADB_X_AALG_NULL &&
+- ((key->sadb_key_bits+7) / 8 == 0 ||
+- (key->sadb_key_bits+7) / 8 > key->sadb_key_len * sizeof(uint64_t)))
++ key->sadb_key_bits == 0)
+ return ERR_PTR(-EINVAL);
+ key = ext_hdrs[SADB_EXT_KEY_ENCRYPT-1];
+ if (key != NULL &&
+ sa->sadb_sa_encrypt != SADB_EALG_NULL &&
+- ((key->sadb_key_bits+7) / 8 == 0 ||
+- (key->sadb_key_bits+7) / 8 > key->sadb_key_len * sizeof(uint64_t)))
++ key->sadb_key_bits == 0)
+ return ERR_PTR(-EINVAL);
+
+ x = xfrm_state_alloc(net);