From: Theodore Ts'o Subject: Re: [PATCH 2/2] fscrypto: don't use on-stack buffer for key derivation Date: Tue, 15 Nov 2016 11:47:04 -0500 Message-ID: <20161115164704.5tzvm2g2x2fyetyu@thunk.org> References: <1478210582-86338-1-git-send-email-ebiggers@google.com> <1478210582-86338-2-git-send-email-ebiggers@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-crypto@vger.kernel.org, jaegeuk@kernel.org, richard@nod.at, luto@kernel.org To: Eric Biggers Return-path: Received: from imap.thunk.org ([74.207.234.97]:51922 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751884AbcKOQrJ (ORCPT ); Tue, 15 Nov 2016 11:47:09 -0500 Content-Disposition: inline In-Reply-To: <1478210582-86338-2-git-send-email-ebiggers@google.com> Sender: linux-crypto-owner@vger.kernel.org List-ID: On Thu, Nov 03, 2016 at 03:03:02PM -0700, Eric Biggers wrote: > With the new (in 4.9) option to use a virtually-mapped stack > (CONFIG_VMAP_STACK), stack buffers cannot be used as input/output for > the scatterlist crypto API because they may not be directly mappable to > struct page. get_crypt_info() was using a stack buffer to hold the > output from the encryption operation used to derive the per-file key. > Fix it by using a heap buffer. > > This bug could most easily be observed in a CONFIG_DEBUG_SG kernel > because this allowed the BUG in sg_set_buf() to be triggered. > > Signed-off-by: Eric Biggers This commit is on the fscrypt and dev branches on ext4.git. - Ted