Linux 4.9.56

Linux 4.9.56

[Greg KH]

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I'm announcing the release of the 4.9.56 kernel.  It fixes a networking
bug in 4.9.55.  Don't use 4.9.55, it's busted, sorry about that, I
should have held off and gotten more testing on it, my fault :(

All users of the 4.9 kernel series must upgrade.

The updated 4.9.y git tree can be found at:
	git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-4.9.y
and can be browsed at the normal kernel.org git web browser:
	http://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary

thanks,

greg k-h

------------

 Makefile          |    2 +-
 net/core/filter.c |   15 ++-------------
 net/core/sock.c   |    5 +----
 3 files changed, 4 insertions(+), 18 deletions(-)

Greg Kroah-Hartman (2):
      Revert "socket, bpf: fix possible use after free"
      Linux 4.9.56


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Re: Linux 4.9.56

[Greg KH]

diff --git a/Makefile b/Makefile
index 2a995675d6bf..feab5f5a507c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 VERSION = 4
 PATCHLEVEL = 9
-SUBLEVEL = 55
+SUBLEVEL = 56
 EXTRAVERSION =
 NAME = Roaring Lionus
 
diff --git a/net/core/filter.c b/net/core/filter.c
index bfeedbbde214..4eb4ce0aeef4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -937,31 +937,20 @@ void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp)
 /* try to charge the socket memory if there is space available
  * return true on success
  */
-static bool __sk_filter_charge(struct sock *sk, struct sk_filter *fp)
+bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
 {
 	u32 filter_size = bpf_prog_size(fp->prog->len);
 
 	/* same check as in sock_kmalloc() */
 	if (filter_size <= sysctl_optmem_max &&
 	    atomic_read(&sk->sk_omem_alloc) + filter_size < sysctl_optmem_max) {
+		atomic_inc(&fp->refcnt);
 		atomic_add(filter_size, &sk->sk_omem_alloc);
 		return true;
 	}
 	return false;
 }
 
-bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
-{
-	if (!atomic_inc_not_zero(&fp->refcnt))
-		return false;
-
-	if (!__sk_filter_charge(sk, fp)) {
-		sk_filter_release(fp);
-		return false;
-	}
-	return true;
-}
-
 static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp)
 {
 	struct sock_filter *old_prog;
diff --git a/net/core/sock.c b/net/core/sock.c
index 2a77cc50f021..231c38d91855 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1528,16 +1528,13 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
 		sock_reset_flag(newsk, SOCK_DONE);
 		skb_queue_head_init(&newsk->sk_error_queue);
 
-		rcu_read_lock();
-		filter = rcu_dereference(sk->sk_filter);
+		filter = rcu_dereference_protected(newsk->sk_filter, 1);
 		if (filter != NULL)
 			/* though it's an empty new sock, the charging may fail
 			 * if sysctl_optmem_max was changed between creation of
 			 * original socket and cloning
 			 */
 			is_charged = sk_filter_charge(newsk, filter);
-		RCU_INIT_POINTER(newsk->sk_filter, filter);
-		rcu_read_unlock();
 
 		if (unlikely(!is_charged || xfrm_sk_clone_policy(newsk, sk))) {
 			/* We need to make sure that we don't uncharge the new