From 4184b2a79a7612a9272ce20d639934584a1f3786 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 10 Nov 2014 18:00:09 +0100 Subject: [PATCH] net: sctp: fix memory leak in auth key management 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 --- net/sctp/auth.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/net/sctp/auth.c b/net/sctp/auth.c index 0e8529113dc5..fb7976aee61c 100644 --- a/net/sctp/auth.c +++ b/net/sctp/auth.c @@ -862,8 +862,6 @@ 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)