From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 769081BDEC; Wed, 3 Jan 2024 17:01:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="aIpcYCAB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B9324C433C7; Wed, 3 Jan 2024 17:01:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1704301305; bh=A2uJKTRhwkWD00fPQfZTXZkdPAI2ZODyov94Bs5Ivk0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aIpcYCABjD29va9NZT3p443h8hq8FCVicZx0is0KdOl3QOBgX/n2eQZD3989+qyQD w11UwB3WgMCsWG5t/Hd5PTOdmnQf2r4GW2CEPU1S6T+4Q7JKM8nwmvK7sqh0+LNV3N u0BJQpEDZ1X7EkdLGQgAHxPhOr3gg1xNlZbyBNsQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, NeilBrown , Jeff Layton , Chuck Lever Subject: [PATCH 6.1 096/100] NFSD: fix possible oops when nfsd/pool_stats is closed. Date: Wed, 3 Jan 2024 17:55:25 +0100 Message-ID: <20240103164910.546486981@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240103164856.169912722@linuxfoundation.org> References: <20240103164856.169912722@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit 88956eabfdea7d01d550535af120d4ef265b1d02 upstream. If /proc/fs/nfsd/pool_stats is open when the last nfsd thread exits, then when the file is closed a NULL pointer is dereferenced. This is because nfsd_pool_stats_release() assumes that the pointer to the svc_serv cannot become NULL while a reference is held. This used to be the case but a recent patch split nfsd_last_thread() out from nfsd_put(), and clearing the pointer is done in nfsd_last_thread(). This is easily reproduced by running rpc.nfsd 8 ; ( rpc.nfsd 0;true) < /proc/fs/nfsd/pool_stats Fortunately nfsd_pool_stats_release() has easy access to the svc_serv pointer, and so can call svc_put() on it directly. Fixes: 9f28a971ee9f ("nfsd: separate nfsd_last_thread() from nfsd_put()") Signed-off-by: NeilBrown Reviewed-by: Jeff Layton Signed-off-by: Chuck Lever Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfssvc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/fs/nfsd/nfssvc.c +++ b/fs/nfsd/nfssvc.c @@ -1124,11 +1124,12 @@ int nfsd_pool_stats_open(struct inode *i int nfsd_pool_stats_release(struct inode *inode, struct file *file) { + struct seq_file *seq = file->private_data; + struct svc_serv *serv = seq->private; int ret = seq_release(inode, file); - struct net *net = inode->i_sb->s_fs_info; mutex_lock(&nfsd_mutex); - nfsd_put(net); + svc_put(serv); mutex_unlock(&nfsd_mutex); return ret; }