From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20150515080531.101230162@1wt.eu> Date: Fri, 15 May 2015 10:05:49 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Daniel Borkmann , Vlad Yasevich , Neil Horman , "David S. Miller" , Ben Hutchings , Willy Tarreau Subject: [ 19/48] net: sctp: fix memory leak in auth key management MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 In-Reply-To: <9c2783dfae10ef2d1e9b08bcc1e562c5@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann commit 4184b2a79a7612a9272ce20d639934584a1f3786 upstream. A very minimal and simple user space application allocating an SCTP socket, setting SCTP_AUTH_KEY setsockopt(2) on it and then closing the socket again will leak the memory containing the authentication key from user space: unreferenced object 0xffff8800837047c0 (size 16): comm "a.out", pid 2789, jiffies 4296954322 (age 192.258s) hex dump (first 16 bytes): 01 00 00 00 04 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [] kmemleak_alloc+0x4e/0xb0 [] __kmalloc+0xe8/0x270 [] sctp_auth_create_key+0x23/0x50 [sctp] [] sctp_auth_set_key+0xa1/0x140 [sctp] [] sctp_setsockopt+0xd03/0x1180 [sctp] [] sock_common_setsockopt+0x14/0x20 [] SyS_setsockopt+0x71/0xd0 [] system_call_fastpath+0x12/0x17 [] 0xffffffffffffffff This is bad because of two things, we can bring down a machine from user space when auth_enable=1, but also we would leave security sensitive keying material in memory without clearing it after use. The issue is that sctp_auth_create_key() already sets the refcount to 1, but after allocation sctp_auth_set_key() does an additional refcount on it, and thus leaving it around when we free the socket. Fixes: 65b07e5d0d0 ("[SCTP]: API updates to suport SCTP-AUTH extensions.") Signed-off-by: Daniel Borkmann Cc: Vlad Yasevich Acked-by: Neil Horman Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings (cherry picked from commit 3af10169145c8eed7b3591c0644da4298405efbc) Signed-off-by: Willy Tarreau --- net/sctp/auth.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/net/sctp/auth.c b/net/sctp/auth.c index 7363b9f..133ce49 100644 --- a/net/sctp/auth.c +++ b/net/sctp/auth.c @@ -865,8 +865,6 @@ int sctp_auth_set_key(struct sctp_endpoint *ep, list_add(&cur_key->key_list, sh_keys); cur_key->key = key; - sctp_auth_key_hold(key); - return 0; nomem: if (!replace) -- 1.7.12.2.21.g234cd45.dirty