linux-kernel - [PATCH 5.12 167/173] NFS: Fix use-after-free in nfs4_init

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210614102703.731316108@linuxfoundation.org>
Date:   Mon, 14 Jun 2021 12:28:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Anna Schumaker <Anna.Schumaker@...app.com>,
        Trond Myklebust <trond.myklebust@...merspace.com>
Subject: [PATCH 5.12 167/173] NFS: Fix use-after-free in nfs4_init_client()

From: Anna Schumaker <Anna.Schumaker@...app.com>

commit 476bdb04c501fc64bf3b8464ffddefc8dbe01577 upstream.

KASAN reports a use-after-free when attempting to mount two different
exports through two different NICs that belong to the same server.

Olga was able to hit this with kernels starting somewhere between 5.7
and 5.10, but I traced the patch that introduced the clear_bit() call to
4.13. So something must have changed in the refcounting of the clp
pointer to make this call to nfs_put_client() the very last one.

Fixes: 8dcbec6d20 ("NFSv41: Handle EXCHID4_FLAG_CONFIRMED_R during NFSv4.1 migration")
Cc: stable@...r.kernel.org # 4.13+
Signed-off-by: Anna Schumaker <Anna.Schumaker@...app.com>
Signed-off-by: Trond Myklebust <trond.myklebust@...merspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/nfs/nfs4client.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -435,8 +435,8 @@ struct nfs_client *nfs4_init_client(stru
 		 */
 		nfs_mark_client_ready(clp, -EPERM);
 	}
-	nfs_put_client(clp);
 	clear_bit(NFS_CS_TSM_POSSIBLE, &clp->cl_flags);
+	nfs_put_client(clp);
 	return old;
 
 error: