linux-kernel - [PATCH] fs: fix KMSAN uninit-value bug by initializing nd in do_file_open

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Message-Id: <20200916052657.18683-1-anant.thazhemadam@gmail.com>
Date:   Wed, 16 Sep 2020 10:56:56 +0530
From:   Anant Thazhemadam <anant.thazhemadam@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     linux-kernel-mentees@...ts.linuxfoundation.org,
        Anant Thazhemadam <anant.thazhemadam@...il.com>,
        syzbot+4191a44ad556eacc1a7a@...kaller.appspotmail.com,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] fs: fix KMSAN uninit-value bug by initializing nd in do_file_open_root

The KMSAN bug report for the bug indicates that there exists;
Local variable ----nd@...file_open_root created at:
 do_file_open_root+0xa4/0xb40 fs/namei.c:3385
 do_file_open_root+0xa4/0xb40 fs/namei.c:3385

Initializing nd fixes this issue, and doesn't break anything else either

Fixes: https://syzkaller.appspot.com/bug?extid=4191a44ad556eacc1a7a
Reported-by: syzbot+4191a44ad556eacc1a7a@...kaller.appspotmail.com
Tested-by: syzbot+4191a44ad556eacc1a7a@...kaller.appspotmail.com
Signed-off-by: Anant Thazhemadam <anant.thazhemadam@...il.com>
---
 fs/namei.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/namei.c b/fs/namei.c
index e99e2a9da0f7..b27382586209 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3404,7 +3404,7 @@ struct file *do_filp_open(int dfd, struct filename *pathname,
 struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 		const char *name, const struct open_flags *op)
 {
-	struct nameidata nd;
+	struct nameidata nd = {};
 	struct file *file;
 	struct filename *filename;
 	int flags = op->lookup_flags | LOOKUP_ROOT;
-- 
2.25.1