[4.2.y-ckt stable] Patch "crypto: af_alg - Forbid bind(2) when nokey child sockets are present" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    crypto: af_alg - Forbid bind(2) when nokey child sockets are present

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt3.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From af0975897f48d824908e2aa9acf0209d0f1e45f3 Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert at gondor.apana.org.au>
Date: Wed, 13 Jan 2016 15:03:32 +0800
Subject: crypto: af_alg - Forbid bind(2) when nokey child sockets are present

commit a6a48c565f6f112c6983e2a02b1602189ed6e26e upstream.

This patch forbids the calling of bind(2) when there are child
sockets created by accept(2) in existence, even if they are created
on the nokey path.

This is needed as those child sockets have references to the tfm
object which bind(2) will destroy.

Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 crypto/af_alg.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index e7cb836..f5e18c2 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -130,19 +130,16 @@ EXPORT_SYMBOL_GPL(af_alg_release);
 void af_alg_release_parent(struct sock *sk)
 {
 	struct alg_sock *ask = alg_sk(sk);
-	bool last;
+	unsigned int nokey = ask->nokey_refcnt;
+	bool last = nokey && !ask->refcnt;

 	sk = ask->parent;
-
-	if (ask->nokey_refcnt && !ask->refcnt) {
-		sock_put(sk);
-		return;
-	}
-
 	ask = alg_sk(sk);

 	lock_sock(sk);
-	last = !--ask->refcnt;
+	ask->nokey_refcnt -= nokey;
+	if (!last)
+		last = !--ask->refcnt;
 	release_sock(sk);

 	if (last)
@@ -188,7 +185,7 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)

 	err = -EBUSY;
 	lock_sock(sk);
-	if (ask->refcnt)
+	if (ask->refcnt | ask->nokey_refcnt)
 		goto unlock;

 	swap(ask->type, type);
@@ -306,6 +303,7 @@ int af_alg_accept(struct sock *sk, struct socket *newsock)

 	if (nokey || !ask->refcnt++)
 		sock_hold(sk);
+	ask->nokey_refcnt += nokey;
 	alg_sk(sk2)->parent = sk;
 	alg_sk(sk2)->type = type;
 	alg_sk(sk2)->nokey_refcnt = nokey;
--
1.9.1