From: Herbert Xu Subject: Re: crypto: algif_hash: creating 0 sized array in hash_accept Date: Mon, 25 Jan 2016 21:58:46 +0800 Message-ID: <20160125135846.GB8256@gondor.apana.org.au> References: <56A6119C.1080203@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , "open list:CRYPTO API" , LKML To: Sasha Levin Return-path: Received: from helcar.hengli.com.au ([209.40.204.226]:47305 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755405AbcAYN6z (ORCPT ); Mon, 25 Jan 2016 08:58:55 -0500 Content-Disposition: inline In-Reply-To: <56A6119C.1080203@oracle.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Mon, Jan 25, 2016 at 07:14:20AM -0500, Sasha Levin wrote: > Hi all, > > While fuzzing with trinity inside a KVM tools guest running the latest -next kernel > I've hit: > > [ 828.386074] UBSAN: Undefined behaviour in crypto/algif_hash.c:185:7 > [ 828.386811] variable length array bound value 0 <= 0 > [ 828.387606] CPU: 1 PID: 17792 Comm: trinity-c313 Not tainted 4.4.0-next-20160122-sasha-00019-gd2a2eb4-dirty #2819 > [ 828.388957] 1ffff10038e06f65 0000000087690421 ffff8801c7037ba8 ffffffffa34474f1 > [ 828.394655] 0000000041b58ab3 ffffffffaf84c518 ffffffffa3447426 ffff8801c7037b70 > [ 828.394684] 0000000087690421 ffffffffb329b1e0 ffff8801c7037c38 0000000000000000 > [ 828.394708] Call Trace: > [ 828.394868] dump_stack (lib/dump_stack.c:52) > [ 828.395040] ? _atomic_dec_and_lock (lib/dump_stack.c:27) > [ 828.395079] ubsan_epilogue (lib/ubsan.c:165) > [ 828.395101] __ubsan_handle_vla_bound_not_positive (lib/ubsan.c:364) > [ 828.395118] ? __ubsan_handle_out_of_bounds (lib/ubsan.c:352) > [ 828.395179] ? sock_alloc_file (net/socket.c:388) > [ 828.395194] ? sock_splice_read (net/socket.c:356) > [ 828.395217] ? check_preemption_disabled (lib/smp_processor_id.c:52) > [ 828.395244] hash_accept (crypto/algif_hash.c:185 (discriminator 1)) > [ 828.395264] SYSC_accept4 (net/socket.c:1476) > [ 828.395282] ? sockfd_lookup_light (net/socket.c:1427) > [ 828.395319] ? _raw_spin_unlock_bh (kernel/locking/spinlock.c:208) > [ 828.395339] ? release_sock (net/core/sock.c:2446) > [ 828.395645] ? hash_accept_parent_nokey (crypto/algif_hash.c:380) > [ 828.396457] ? map_id_down (kernel/user_namespace.c:201) > [ 828.396484] ? SyS_futex (kernel/futex.c:3099) > [ 828.396502] ? do_futex (kernel/futex.c:3099) > [ 828.396519] ? SyS_socket (net/socket.c:1213) > [ 828.396536] ? move_addr_to_kernel (net/socket.c:1213) > [ 828.396552] SyS_accept (net/socket.c:1506) > [ 828.396569] entry_SYSCALL_64_fastpath (arch/x86/entry/entry_64.S:186) > [ 828.396596] ? vm_mmap_pgoff (mm/util.c:325) > > Which is this code snippet: > > static int hash_accept(struct socket *sock, struct socket *newsock, int flags) > { > struct sock *sk = sock->sk; > struct alg_sock *ask = alg_sk(sk); > struct hash_ctx *ctx = ask->private; > struct ahash_request *req = &ctx->req; > char state[crypto_ahash_statesize(crypto_ahash_reqtfm(req))]; > > > Where crypto_ahash_statesize(crypto_ahash_reqtfm(req)) == 0. This should not be possible because we forbid any algorithm with a zero statesize from being registered. Please tell us what algorithm you were using that led to this crash. Thanks, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt