4.4-stable review patch. If anyone has any objections, please let me know.
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From: Li RongQing lirongqing@baidu.com
[ Upstream commit 9b42d55a66d388e4dd5550107df051a9637564fc ]
socket can be disconnected and gets transformed back to a listening socket, if sk_frag.page is not released, which will be cloned into a new socket by sk_clone_lock, but the reference count of this page is increased, lead to a use after free or double free issue
Signed-off-by: Li RongQing lirongqing@baidu.com Cc: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/ipv4/tcp.c | 6 ++++++ 1 file changed, 6 insertions(+)
--- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2276,6 +2276,12 @@ int tcp_disconnect(struct sock *sk, int
WARN_ON(inet->inet_num && !icsk->icsk_bind_hash);
+ if (sk->sk_frag.page) { + put_page(sk->sk_frag.page); + sk->sk_frag.page = NULL; + sk->sk_frag.offset = 0; + } + sk->sk_error_report(sk); return err; }