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Date: Mon, 29 Dec 2014 02:11:31 +0100 From: Ben Hutchings <ben@...adent.org.uk> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org CC: akpm@...ux-foundation.org, "Neil Horman" <nhorman@...driver.com>, "Vlad Yasevich" <vyasevich@...il.com>, "Daniel Borkmann" <dborkman@...hat.com>, "David S. Miller" <davem@...emloft.net> Subject: [PATCH 3.2 20/27] net: sctp: fix memory leak in auth key management 3.2.66-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Daniel Borkmann <dborkman@...hat.com> 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: [<ffffffff816d7e8e>] kmemleak_alloc+0x4e/0xb0 [<ffffffff811c88d8>] __kmalloc+0xe8/0x270 [<ffffffffa0870c23>] sctp_auth_create_key+0x23/0x50 [sctp] [<ffffffffa08718b1>] sctp_auth_set_key+0xa1/0x140 [sctp] [<ffffffffa086b383>] sctp_setsockopt+0xd03/0x1180 [sctp] [<ffffffff815bfd94>] sock_common_setsockopt+0x14/0x20 [<ffffffff815beb61>] SyS_setsockopt+0x71/0xd0 [<ffffffff816e58a9>] system_call_fastpath+0x12/0x17 [<ffffffffffffffff>] 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 <dborkman@...hat.com> Cc: Vlad Yasevich <vyasevich@...il.com> Acked-by: Neil Horman <nhorman@...driver.com> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Ben Hutchings <ben@...adent.org.uk> --- net/sctp/auth.c | 2 -- 1 file changed, 2 deletions(-) --- a/net/sctp/auth.c +++ b/net/sctp/auth.c @@ -866,8 +866,6 @@ int sctp_auth_set_key(struct sctp_endpoi list_add(&cur_key->key_list, sh_keys); cur_key->key = key; - sctp_auth_key_hold(key); - return 0; nomem: if (!replace) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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