From patchwork Mon Jun 24 16:27:39 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Snitzer X-Patchwork-Id: 13709837 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 EC95C19DF65 for ; Mon, 24 Jun 2024 16:28:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719246488; cv=none; b=czcsRP3Fo4YdecG9zqsFZD1fFN5D2TMgoa7rHeg4FszNZrhdVuj7J6j6qFqNXYxgLltF7oc9ikt7AqtS7HGw3d0ExWZ+ETe7qE31cLZ7+TEnBedrgFH3CbTT8JcaRQ6ISCm2PLRsQGCcaJeo1iYE45CLQEvt0OW+t9vweJsx0B0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719246488; c=relaxed/simple; bh=tuIJUU+UKRHC/fDd2tlDYJc70zfPxdAygdj0ZUkU1Xc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BA6mfXSMZ4nKh7ibB4A48LZy70zS0qbpK1R3mW+Gxq9OGDGNt0lkJmSmyzEifgpxEYmXxBNXwGlTYjuDDjN3QewzlEVF+GkEFdjqIuMFEEE9bEYNPdrAHbhUHRODoPalYCsNijCV4MlEHkYfxemiRdaTV6SDvYvbCfvT0TMbtQs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MEi0IoKx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MEi0IoKx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5AD79C2BBFC; Mon, 24 Jun 2024 16:28:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1719246487; bh=tuIJUU+UKRHC/fDd2tlDYJc70zfPxdAygdj0ZUkU1Xc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MEi0IoKxH9YgyxYP7UPX77pQVJU/rNDxumgw/L95YmA+DW2AQn8VijxWpB0WeaQmK jakU1eoyzKJwlo7Z6kKfDMSLqbYA/mMWtUdZHSjXrjTfPBCr8LysSzFq6cECXfchgX /txAjDXRx/HssDO2reLFhP2EBJubslkjhOr6I8dL6BkuH+mcyofu0TLLKG1dDatoce 1AD5cgZY95XH8ibka1sIvJ4OLQwCKTAhkWek32xn1vi5l29V91qfOH420raKBamCZt niEeklVR48acRRxLjlnwKaU5rMR44B6cibWQWtzQcDEsmQ8Yyekn4l0w8DLXQ0kd9K abin4fFRRErSg== From: Mike Snitzer To: linux-nfs@vger.kernel.org Cc: Jeff Layton , Chuck Lever , Trond Myklebust , NeilBrown , snitzer@hammerspace.com Subject: [PATCH v7 18/20] nfsd/localio: use SRCU to dereference nn->nfsd_serv in nfsd_open_local_fh Date: Mon, 24 Jun 2024 12:27:39 -0400 Message-ID: <20240624162741.68216-19-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240624162741.68216-1-snitzer@kernel.org> References: <20240624162741.68216-1-snitzer@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Use nfsd_serv_get to SRCU deference nn->nfsd_serv and pass the resulting svc_serv to nfsd_local_fakerqst_create, open the file handle and then drop the reference using nfsd_serv_put at the end of nfsd_open_local_fh. Verified to fix an easy to hit crash that would occur if an nfsd instance running in a container, with a localio client mounted, is shutdown. Upon restart of the container and associated nfsd the client would go on to crash due to NULL pointer dereference that occuured due to the nfs client's localio attempting to nfsd_open_local_fh(), using nn->nfsd_serv, without having a proper reference on nn->nfsd_serv. Signed-off-by: Mike Snitzer --- fs/nfsd/localio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/localio.c b/fs/nfsd/localio.c index aaa5293eb352..4c54905dca14 100644 --- a/fs/nfsd/localio.c +++ b/fs/nfsd/localio.c @@ -191,6 +191,7 @@ int nfsd_open_local_fh(struct net *net, struct nfsd_file *nf; int status = 0; int mayflags = NFSD_MAY_LOCALIO; + int srcu_idx; struct svc_serv *serv; __be32 beres; @@ -205,7 +206,7 @@ int nfsd_open_local_fh(struct net *net, } nn = net_generic(net, nfsd_net_id); - serv = READ_ONCE(nn->nfsd_serv); + serv = nfsd_serv_get(nn, &srcu_idx); if (unlikely(!serv)) { dprintk("%s: localio denied. Server not running\n", __func__); status = -ENXIO; @@ -245,6 +246,7 @@ int nfsd_open_local_fh(struct net *net, out_revertcred: revert_creds(save_cred); out_net: + nfsd_serv_put(nn, srcu_idx); put_net(net); return status; }