From e40607cbe270a9e8360907cb1e62ddf0736e4864 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 10 Nov 2014 17:54:26 +0100 Subject: net: sctp: fix NULL pointer dereference in af->from_addr_param on malformed packet An SCTP server doing ASCONF will panic on malformed INIT ping-of-death in the form of: ------------ INIT[PARAM: SET_PRIMARY_IP] ------------> While the INIT chunk parameter verification dissects through many things in order to detect malformed input, it misses to actually check parameters inside of parameters. E.g. RFC5061, section 4.2.4 proposes a 'set primary IP address' parameter in ASCONF, which has as a subparameter an address parameter. So an attacker may send a parameter type other than SCTP_PARAM_IPV4_ADDRESS or SCTP_PARAM_IPV6_ADDRESS, param_type2af() will subsequently return 0 and thus sctp_get_af_specific() returns NULL, too, which we then happily dereference unconditionally through af->from_addr_param(). The trace for the log: BUG: unable to handle kernel NULL pointer dereference at 0000000000000078 IP: [] sctp_process_init+0x492/0x990 [sctp] PGD 0 Oops: 0000 [#1] SMP [...] Pid: 0, comm: swapper Not tainted 2.6.32-504.el6.x86_64 #1 Bochs Bochs RIP: 0010:[] [] sctp_process_init+0x492/0x990 [sctp] [...] Call Trace: [] ? sctp_bind_addr_copy+0x5d/0xe0 [sctp] [] sctp_sf_do_5_1B_init+0x21b/0x340 [sctp] [] sctp_do_sm+0x71/0x1210 [sctp] [] ? sctp_endpoint_lookup_assoc+0xc9/0xf0 [sctp] [] sctp_endpoint_bh_rcv+0x116/0x230 [sctp] [] sctp_inq_push+0x56/0x80 [sctp] [] sctp_rcv+0x982/0xa10 [sctp] [] ? ipt_local_in_hook+0x23/0x28 [iptable_filter] [] ? nf_iterate+0x69/0xb0 [] ? ip_local_deliver_finish+0x0/0x2d0 [] ? nf_hook_slow+0x76/0x120 [] ? ip_local_deliver_finish+0x0/0x2d0 [...] A minimal way to address this is to check for NULL as we do on all other such occasions where we know sctp_get_af_specific() could possibly return with NULL. Fixes: d6de3097592b ("[SCTP]: Add the handling of "Set Primary IP Address" parameter to INIT") Signed-off-by: Daniel Borkmann Cc: Vlad Yasevich Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/sm_make_chunk.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'net/sctp') diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c index ab734be8cb20..9f32741abb1c 100644 --- a/net/sctp/sm_make_chunk.c +++ b/net/sctp/sm_make_chunk.c @@ -2609,6 +2609,9 @@ do_addr_param: addr_param = param.v + sizeof(sctp_addip_param_t); af = sctp_get_af_specific(param_type2af(param.p->type)); + if (af == NULL) + break; + af->from_addr_param(&addr, addr_param, htons(asoc->peer.port), 0); -- cgit v1.2.1 From 4184b2a79a7612a9272ce20d639934584a1f3786 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Mon, 10 Nov 2014 18:00:09 +0100 Subject: 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(-) (limited to 'net/sctp') 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) -- cgit v1.2.1