From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 26 Apr 2018 09:14:01 +0000 (+0200)
Subject: 4.4-stable patches
X-Git-Tag: v3.18.107~32
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5e7e24e71f49151236ed2e4a398a777ba75c8791;p=thirdparty%2Fkernel%2Fstable-queue.git

4.4-stable patches

added patches:
	socket-bpf-fix-possible-use-after-free.patch
---

diff --git a/queue-4.4/series b/queue-4.4/series
index 5328ecbdb27..2a67e8031da 100644
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -6,3 +6,4 @@ r8152-add-linksys-usb3gigv1-id.patch
 input-drv260x-fix-initializing-overdrive-voltage.patch
 ath9k_hw-check-if-the-chip-failed-to-wake-up.patch
 jbd2-fix-use-after-free-in-kjournald2.patch
+socket-bpf-fix-possible-use-after-free.patch
diff --git a/queue-4.4/socket-bpf-fix-possible-use-after-free.patch b/queue-4.4/socket-bpf-fix-possible-use-after-free.patch
new file mode 100644
index 00000000000..42e6bb43188
--- /dev/null
+++ b/queue-4.4/socket-bpf-fix-possible-use-after-free.patch
@@ -0,0 +1,86 @@
+From 02f7e4101092b88e57c73171174976c8a72a3eba Mon Sep 17 00:00:00 2001
+From: Eric Dumazet <edumazet@google.com>
+Date: Mon, 2 Oct 2017 12:20:51 -0700
+Subject: socket, bpf: fix possible use after free
+
+From: Eric Dumazet <edumazet@google.com>
+
+commit eefca20eb20c66b06cf5ed09b49b1a7caaa27b7b upstream
+
+Starting from linux-4.4, 3WHS no longer takes the listener lock.
+
+Since this time, we might hit a use-after-free in sk_filter_charge(),
+if the filter we got in the memcpy() of the listener content
+just happened to be replaced by a thread changing listener BPF filter.
+
+To fix this, we need to make sure the filter refcount is not already
+zero before incrementing it again.
+
+Fixes: e994b2f0fb92 ("tcp: do not lock listener to process SYN packets")
+Signed-off-by: Eric Dumazet <edumazet@google.com>
+Acked-by: Alexei Starovoitov <ast@kernel.org>
+Acked-by: Daniel Borkmann <daniel@iogearbox.net>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+Cc: Zubin Mithra <zsm@google.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ net/core/filter.c |   15 +++++++++++++--
+ net/core/sock.c   |    5 ++++-
+ 2 files changed, 17 insertions(+), 3 deletions(-)
+
+--- a/net/core/filter.c
++++ b/net/core/filter.c
+@@ -920,20 +920,31 @@ void sk_filter_uncharge(struct sock *sk,
+ /* try to charge the socket memory if there is space available
+  * return true on success
+  */
+-bool sk_filter_charge(struct sock *sk, struct sk_filter *fp)
++static 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;
+--- a/net/core/sock.c
++++ b/net/core/sock.c
+@@ -1550,13 +1550,16 @@ struct sock *sk_clone_lock(const struct
+ 		sock_reset_flag(newsk, SOCK_DONE);
+ 		skb_queue_head_init(&newsk->sk_error_queue);
+ 
+-		filter = rcu_dereference_protected(newsk->sk_filter, 1);
++		rcu_read_lock();
++		filter = rcu_dereference(sk->sk_filter);
+ 		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