linux-kernel - Re: "Switch !O_CREAT case to use of do

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Message-ID: <20100306184107.GH30031@ZenIV.linux.org.uk>
Date:	Sat, 6 Mar 2010 18:41:07 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, walt <w41ter@...il.com>
Subject: Re: "Switch !O_CREAT case to use of do_last()" causes segfault in
 glibc

On Sat, Mar 06, 2010 at 06:32:54PM +0000, Al Viro wrote:
> On Sat, Mar 06, 2010 at 10:20:41AM -0800, walt wrote:
> > On 03/06/2010 10:03 AM, Al Viro wrote:
> > 
> > >_Really_ interesting; it doesn't look like an oops - smells like an attempt
> > >to do opendir() that fails for some reason, goes unnoticed and resulting
> > >FILE * (i.e. NULL) is fed to readdir()?
> > >
> > >What does it attempt to open?
> > 
> > Ah, this may help:
> > 
> > open("/usr/share/zoneinfo/", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 47
> > open("/usr/share/zoneinfo/MST7MDT", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 48
> 
> Now that is interesting.  Looks like it has managed to lose O_DIRECTORY check
> in the open without trailing slash and (properly) barfed with / added.

OK, I can reproduce it.  Give me a few, I'll see...

AAARGH.

Fix a dumb typo - use of & instead of &&

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---

diff --git a/fs/namei.c b/fs/namei.c
index 3d9d2f9..48e60a1 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1656,7 +1656,7 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
 		if (path->dentry->d_inode->i_op->follow_link)
 			return NULL;
 		error = -ENOTDIR;
-		if (*want_dir & !path->dentry->d_inode->i_op->lookup)
+		if (*want_dir && !path->dentry->d_inode->i_op->lookup)
 			goto exit_dput;
 		path_to_nameidata(path, nd);
 		audit_inode(pathname, nd->path.dentry);
--
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