From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: Re: v2.6.28-rc1: readlink /proc/*/exe returns uninitialized data to userspace Date: Tue, 4 Nov 2008 15:12:35 +0000 Message-ID: <20081104151234.GH28946@ZenIV.linux.org.uk> References: <19f34abd0810251014s7968557br38e43aa0b9cdcf09@mail.gmail.com> <200810252241.53601.rjw@sisk.pl> <19f34abd0810261408w61b1e2dbvb9a0e16ce5a10022@mail.gmail.com> <19f34abd0811040139t8334502i7a5d8501c5fe95ac@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "Eric W. Biederman" , "Koyama, Yoshiya" , "Rafael J. Wysocki" , Alexey Dobriyan , Ingo Molnar , Pekka Enberg , LKML , Greg KH , Kay Sievers , linux-fsdevel@vger.kernel.org To: Vegard Nossum Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:45357 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753077AbYKDPNA (ORCPT ); Tue, 4 Nov 2008 10:13:00 -0500 Content-Disposition: inline In-Reply-To: <19f34abd0811040139t8334502i7a5d8501c5fe95ac@mail.gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Nov 04, 2008 at 10:39:19AM +0100, Vegard Nossum wrote: > On Sun, Oct 26, 2008 at 10:08 PM, Vegard Nossum wrote: > # uname -a > Linux localhost.localdomain 2.6.25.11-97.fc9.i686 #1 SMP Mon Jul 21 > 01:31:09 EDT 2008 i686 i686 i386 GNU/Linux > # prelink -mRf /sbin/udevd > # ./a.out /proc/564/exe > warning: /proc/564/exe: got return value 38, expected 11 > 2f7362696e2f7564657664005f47387942426e5952446e566f306868202864656c6574656429 > /sbin/udevd _G8yBBnYRDnVo0hh (deleted) > > Yoshiya Koyama reports that the problem exists on RHEL 2.6.9-42.ELsmp too. > > I don't think it's exactly the same problem as originally reported, > because I definitely wasn't using prelinking (the prelink binary > wasn't even installed on the machine until today). But finding the > root cause of this may solve both problems. switch_names() buggered in case of short names on both sides. That should help: >>From 2acda856910b774717e0290bbf948c7dee0f2e1a Mon Sep 17 00:00:00 2001 From: Al Viro Date: Mon, 3 Nov 2008 15:03:50 -0500 Subject: [PATCH] fix switch_names() breakage in short-to-short case We want ->name.len to match the resulting name on *both* source and target Signed-off-by: Al Viro --- fs/dcache.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/dcache.c b/fs/dcache.c index a1d86c7..15e4f83 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1620,8 +1620,11 @@ static void switch_names(struct dentry *dentry, struct dentry *target) */ memcpy(dentry->d_iname, target->d_name.name, target->d_name.len + 1); + dentry->d_name.len = target->d_name.len; + return; } } + do_switch(dentry->d_name.len, target->d_name.len); } /* @@ -1681,7 +1684,6 @@ already_unhashed: /* Switch the names.. */ switch_names(dentry, target); - do_switch(dentry->d_name.len, target->d_name.len); do_switch(dentry->d_name.hash, target->d_name.hash); /* ... and switch the parents */ @@ -1791,7 +1793,6 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon) struct dentry *dparent, *aparent; switch_names(dentry, anon); - do_switch(dentry->d_name.len, anon->d_name.len); do_switch(dentry->d_name.hash, anon->d_name.hash); dparent = dentry->d_parent; -- 1.5.6.5