From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 11 Jan 2018 12:01:19 -0500 From: Theodore Ts'o Message-ID: <20180111170119.GB19241@thunk.org> References: <1515636190-24061-1-git-send-email-keescook@chromium.org> <1515636190-24061-14-git-send-email-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1515636190-24061-14-git-send-email-keescook@chromium.org> Subject: [kernel-hardening] Re: [PATCH 13/38] ext4: Define usercopy region in ext4_inode_cache slab cache To: Kees Cook Cc: linux-kernel@vger.kernel.org, David Windsor , Andreas Dilger , linux-ext4@vger.kernel.org, Linus Torvalds , Alexander Viro , Andrew Morton , Andy Lutomirski , Christoph Hellwig , Christoph Lameter , "David S. Miller" , Laura Abbott , Mark Rutland , "Martin K. Petersen" , Paolo Bonzini , Christian Borntraeger , Christoffer Dall , Dave Kleikamp , Jan Kara , Luis de Bethencourt , Marc Zyngier , Rik van Riel , Matthew Garrett , linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, netdev@vger.kernel.org, linux-mm@kvack.org, kernel-hardening@lists.openwall.com List-ID: On Wed, Jan 10, 2018 at 06:02:45PM -0800, Kees Cook wrote: > The ext4 symlink pathnames, stored in struct ext4_inode_info.i_data > and therefore contained in the ext4_inode_cache slab cache, need > to be copied to/from userspace. Symlink operations to/from userspace aren't common or in the hot path, and when they are in i_data, limited to at most 60 bytes. Is it worth it to copy through a bounce buffer so as to disallow any usercopies into struct ext4_inode_info? - Ted