Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758401AbYLKUGk (ORCPT ); Thu, 11 Dec 2008 15:06:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756779AbYLKUG3 (ORCPT ); Thu, 11 Dec 2008 15:06:29 -0500 Received: from e4.ny.us.ibm.com ([32.97.182.144]:42637 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756541AbYLKUG2 (ORCPT ); Thu, 11 Dec 2008 15:06:28 -0500 Subject: Re: [PATCH] JFS: ensure link targets are NULL-terminated From: Dave Kleikamp To: Duane Griffin Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Boaz Harrosh , Dave.Kleikamp.shaggy@austin.ibm.com, jfs-discussion@lists.sourceforge.net In-Reply-To: <1229022995-9898-9-git-send-email-duaneg@dghda.com> References: <1229022995-9898-1-git-send-email-duaneg@dghda.com> <1229022995-9898-2-git-send-email-duaneg@dghda.com> <1229022995-9898-3-git-send-email-duaneg@dghda.com> <1229022995-9898-4-git-send-email-duaneg@dghda.com> <1229022995-9898-5-git-send-email-duaneg@dghda.com> <1229022995-9898-6-git-send-email-duaneg@dghda.com> <1229022995-9898-7-git-send-email-duaneg@dghda.com> <1229022995-9898-8-git-send-email-duaneg@dghda.com> <1229022995-9898-9-git-send-email-duaneg@dghda.com> Content-Type: text/plain Date: Thu, 11 Dec 2008 14:06:11 -0600 Message-Id: <1229025971.9245.18.camel@norville.austin.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2176 Lines: 69 On Thu, 2008-12-11 at 19:16 +0000, Duane Griffin wrote: > Ensure link targets are NULL-terminated, even if corrupted on-disk. > > Signed-off-by: Duane Griffin > --- > fs/jfs/symlink.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/fs/jfs/symlink.c b/fs/jfs/symlink.c > index 4af1a05..f5f1b5d 100644 > --- a/fs/jfs/symlink.c > +++ b/fs/jfs/symlink.c > @@ -18,6 +18,7 @@ > > #include > #include > +#include "jfs_filsys.h" > #include "jfs_incore.h" > #include "jfs_inode.h" > #include "jfs_xattr.h" > @@ -25,6 +26,7 @@ > static void *jfs_follow_link(struct dentry *dentry, struct nameidata *nd) > { > char *s = JFS_IP(dentry->d_inode)->i_inline; > + s[IDATASIZE - 1] = '\0'; > nd_set_link(nd, s); > return NULL; > } Thanks. I came up with an alternate patch that I like slightly better. This one null-terminates the string when the inode is read rather than every time the link is followed, and at the proper place (i_size). It's not a big deal, since the symlink will be corrupted either way. What do you think of this patch? Signed-off-by: Dave Kleikamp diff --git a/fs/jfs/inode.c b/fs/jfs/inode.c index 2103397..b00ee9f 100644 --- a/fs/jfs/inode.c +++ b/fs/jfs/inode.c @@ -59,8 +59,14 @@ struct inode *jfs_iget(struct super_block *sb, unsigned long ino) if (inode->i_size >= IDATASIZE) { inode->i_op = &page_symlink_inode_operations; inode->i_mapping->a_ops = &jfs_aops; - } else + } else { inode->i_op = &jfs_symlink_inode_operations; + /* + * The inline data should be null-terminated, but + * don't let on-disk corruption crash the kernel + */ + JFS_IP(inode)->i_inline[inode->i_size] = '\0'; + } } else { inode->i_op = &jfs_file_inode_operations; init_special_inode(inode, inode->i_mode, inode->i_rdev); -- David Kleikamp IBM Linux Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/