From patchwork Fri Jun 14 03:44:26 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Snitzer X-Patchwork-Id: 13697850 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 386FD1474A3 for ; Fri, 14 Jun 2024 03:44:52 +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=1718336692; cv=none; b=AwOlCuKon4CrmN6H5CASw+9UGtlXOswqemrJsKj1a80Gvpek7RuPZWt8zrmLriXU4e7b6iW4mD1rnDMxxFFlD1QNIeG+0xZBm/gvXs+8M39OpwyTvnPTvOSDYDaqW3E0swAhb0VLnL60ANwW1PpkpRUPIqVr2+554IHVvQ/Pmng= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718336692; c=relaxed/simple; bh=FCw8d7u3yE/Yb082AyvJ4nrRXY5ztvkcW1gDSsH/7bI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=i3JyC3IMX6Y2nkiOAX7RkTJrHjxpzoT+9a7bDbC05qHQbbUlNgNm4lRYqyS4PFFpJOO/GGyTTWNiO4yXjwWvTBxhDVtLfyI7GJXGdkMK5C8LEZY2pTCdcVXFye+7pBG9p8rSfyhIUexzhROXaV7EvZplRIGakYw9t/JNSkyK9hM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GvUrPnwZ; 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="GvUrPnwZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9BF1C2BBFC; Fri, 14 Jun 2024 03:44:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718336692; bh=FCw8d7u3yE/Yb082AyvJ4nrRXY5ztvkcW1gDSsH/7bI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GvUrPnwZHGyld0Vv90wsNlDv6smoEeXRZ/GxfbJzZ14L9puHoRAScb61GCuBwMmbc fTtDsfhCdxugCts6RIOa1a/SgAG21YLu49DxEesATZtwzMATXgPkxeKoyiqERFPtSj ZGyeseb2pZqnO1NDLa5DxOXGGPulmG+POm7DDLJRjif/tA3jfUe/nWSU9zLfA0+SFm ckvp2nN/ZXm0prkc1J3hAoFmS8SFvgoAg1bqR83WSc+GXffcngBU1nWC04u3vcIDIx OuHc0MXHFU5hOieB0Vx275bR9lBBihwEYnMaPBaGUWylOVVjgE8HxCNCEoPU+lZCkV p3iF9EfKj76ww== From: Mike Snitzer To: linux-nfs@vger.kernel.org Cc: Jeff Layton , Chuck Lever , Trond Myklebust , NeilBrown , snitzer@hammerspace.com Subject: [PATCH v3 18/18] nfsd/localio: use nfsd_serv_get/put in nfsd_open_local_fh Date: Thu, 13 Jun 2024 23:44:26 -0400 Message-ID: <20240614034426.31043-19-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240614034426.31043-1-snitzer@kernel.org> References: <20240614034426.31043-1-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 cdf8e115b33e..d1d9fbaab82e 100644 --- a/fs/nfsd/localio.c +++ b/fs/nfsd/localio.c @@ -193,6 +193,7 @@ 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; @@ -207,7 +208,7 @@ 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; @@ -247,6 +248,7 @@ 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; }