From: Al Viro <viro@zeniv.linux.org.uk>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Anant Thazhemadam <anant.thazhemadam@gmail.com>,
syzbot+4191a44ad556eacc1a7a@syzkaller.appspotmail.com,
linux-kernel@vger.kernel.org, Eric Biggers <ebiggers@kernel.org>,
linux-fsdevel@vger.kernel.org,
linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [Linux-kernel-mentees] [PATCH] fs: fix KMSAN uninit-value bug by initializing nd in do_file_open_root
Date: Sat, 19 Sep 2020 17:55:58 +0100 [thread overview]
Message-ID: <20200919165558.GH3421308@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20200919161727.GG3421308@ZenIV.linux.org.uk>
On Sat, Sep 19, 2020 at 05:17:27PM +0100, Al Viro wrote:
> Lovely... That would get an empty path and non-directory for a starting
> point, but it should end up with LAST_ROOT in nd->last_type. Which should
> not be able to reach the readers of those fields... Which kernel had
> that been on?
Yecchhh... I see what's going on; I suspect that this ought to be enough.
Folks, could somebody test it on the original reproducer setup?
diff --git a/fs/namei.c b/fs/namei.c
index e99e2a9da0f7..3f02cae7e73f 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2113,8 +2113,10 @@ static int link_path_walk(const char *name, struct nameidata *nd)
return PTR_ERR(name);
while (*name=='/')
name++;
- if (!*name)
+ if (!*name) {
+ nd->dir_mode = 0; // short-circuit the 'hardening' idiocy
return 0;
+ }
/* At this point we know we have a real path component. */
for(;;) {
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next prev parent reply other threads:[~2020-09-19 16:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 5:26 [Linux-kernel-mentees] [PATCH] fs: fix KMSAN uninit-value bug by initializing nd in do_file_open_root Anant Thazhemadam
2020-09-16 5:41 ` Eric Biggers
2020-09-17 0:22 ` Al Viro
2020-09-19 14:44 ` Greg KH
2020-09-19 16:17 ` Al Viro
2020-09-19 16:55 ` Al Viro [this message]
2020-09-19 11:33 ` Anant Thazhemadam
2020-09-19 20:17 ` Anant Thazhemadam
2020-10-04 15:25 ` Anant Thazhemadam
2020-09-16 6:16 ` Greg KH
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