From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755316AbdL1SV4 (ORCPT ); Thu, 28 Dec 2017 13:21:56 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:58756 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753997AbdL1RNQ (ORCPT ); Thu, 28 Dec 2017 12:13:16 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Herbert Xu" , "Eric Biggers" , "syzbot" Date: Thu, 28 Dec 2017 16:59:12 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 92/94] crypto: salsa20 - fix blkcipher_walk API usage In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.97-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit ecaaab5649781c5a0effdaf298a925063020500e upstream. When asked to encrypt or decrypt 0 bytes, both the generic and x86 implementations of Salsa20 crash in blkcipher_walk_done(), either when doing 'kfree(walk->buffer)' or 'free_page((unsigned long)walk->page)', because walk->buffer and walk->page have not been initialized. The bug is that Salsa20 is calling blkcipher_walk_done() even when nothing is in 'walk.nbytes'. But blkcipher_walk_done() is only meant to be called when a nonzero number of bytes have been provided. The broken code is part of an optimization that tries to make only one call to salsa20_encrypt_bytes() to process inputs that are not evenly divisible by 64 bytes. To fix the bug, just remove this "optimization" and use the blkcipher_walk API the same way all the other users do. Reproducer: #include #include #include int main() { int algfd, reqfd; struct sockaddr_alg addr = { .salg_type = "skcipher", .salg_name = "salsa20", }; char key[16] = { 0 }; algfd = socket(AF_ALG, SOCK_SEQPACKET, 0); bind(algfd, (void *)&addr, sizeof(addr)); reqfd = accept(algfd, 0, 0); setsockopt(algfd, SOL_ALG, ALG_SET_KEY, key, sizeof(key)); read(reqfd, key, sizeof(key)); } Reported-by: syzbot Fixes: eb6f13eb9f81 ("[CRYPTO] salsa20_generic: Fix multi-page processing") Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu Signed-off-by: Ben Hutchings --- arch/x86/crypto/salsa20_glue.c | 7 ------- crypto/salsa20_generic.c | 7 ------- 2 files changed, 14 deletions(-) --- a/arch/x86/crypto/salsa20_glue.c +++ b/arch/x86/crypto/salsa20_glue.c @@ -64,13 +64,6 @@ static int encrypt(struct blkcipher_desc salsa20_ivsetup(ctx, walk.iv); - if (likely(walk.nbytes == nbytes)) - { - salsa20_encrypt_bytes(ctx, walk.src.virt.addr, - walk.dst.virt.addr, nbytes); - return blkcipher_walk_done(desc, &walk, 0); - } - while (walk.nbytes >= 64) { salsa20_encrypt_bytes(ctx, walk.src.virt.addr, walk.dst.virt.addr, --- a/crypto/salsa20_generic.c +++ b/crypto/salsa20_generic.c @@ -188,13 +188,6 @@ static int encrypt(struct blkcipher_desc salsa20_ivsetup(ctx, walk.iv); - if (likely(walk.nbytes == nbytes)) - { - salsa20_encrypt_bytes(ctx, walk.dst.virt.addr, - walk.src.virt.addr, nbytes); - return blkcipher_walk_done(desc, &walk, 0); - } - while (walk.nbytes >= 64) { salsa20_encrypt_bytes(ctx, walk.dst.virt.addr, walk.src.virt.addr,