From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:44312 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726638AbfAGXQh (ORCPT ); Mon, 7 Jan 2019 18:16:37 -0500 From: Eric Biggers To: stable@vger.kernel.org, Greg Kroah-Hartman Cc: linux-crypto@vger.kernel.org, Martin Willi , Ard Biesheuvel Subject: [PATCH 4.9,4.4] crypto: x86/chacha20 - avoid sleeping with preemption disabled Date: Mon, 7 Jan 2019 15:15:59 -0800 Message-Id: <20190107231559.13357-1-ebiggers@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-crypto-owner@vger.kernel.org List-ID: From: Eric Biggers Hi Greg, please consider applying this to 4.9-stable and 4.4-stable. It's a minimal fix for a bug that was fixed incidentally by a large refactoring in v4.11. >8------------------------------------------------------8< In chacha20-simd, clear the MAY_SLEEP flag in the blkcipher_desc to prevent sleeping with preemption disabled, under kernel_fpu_begin(). This was fixed upstream incidentally by a large refactoring, commit 9ae433bc79f9 ("crypto: chacha20 - convert generic and x86 versions to skcipher"). But syzkaller easily trips over this when running on older kernels, as it's easily reachable via AF_ALG. Therefore, this patch makes the minimal fix for older kernels. Fixes: c9320b6dcb89 ("crypto: chacha20 - Add a SSSE3 SIMD variant for x86_64") Cc: linux-crypto@vger.kernel.org Cc: Martin Willi Cc: Ard Biesheuvel Signed-off-by: Eric Biggers --- arch/x86/crypto/chacha20_glue.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/crypto/chacha20_glue.c b/arch/x86/crypto/chacha20_glue.c index f910d1d449f00..0a5fedf43bdc8 100644 --- a/arch/x86/crypto/chacha20_glue.c +++ b/arch/x86/crypto/chacha20_glue.c @@ -77,6 +77,7 @@ static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst, blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE); + desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv); -- 2.20.1.97.g81188d93c3-goog