From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Date: Tue, 31 Dec 2019 15:24:55 +0000 Subject: [PATCH 2/3] afs: Fix use-after-loss-of-ref Message-Id: <157780589537.25571.1965637589354532477.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <157780588822.25571.7926816048227538205.stgit@warthog.procyon.org.uk> In-Reply-To: <157780588822.25571.7926816048227538205.stgit@warthog.procyon.org.uk> To: linux-afs@lists.infradead.org Cc: Al Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, keyrings@vger.kernel.org, dhowells@redhat.com afs_lookup() has a tracepoint to indicate the outcome of d_splice_alias(), passing it the inode to retrieve the fid from. However, the function gave up its ref on that inode when it called d_splice_alias(), which may have failed and dropped the inode. Fix this by caching the fid. Fixes: 80548b03991f ("afs: Add more tracepoints") Reported-by: Al Viro Signed-off-by: David Howells --- fs/afs/dir.c | 12 +++++++----- include/trace/events/afs.h | 12 +++--------- 2 files changed, 10 insertions(+), 14 deletions(-) diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 497f979018c2..813db1708494 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -908,6 +908,7 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { struct afs_vnode *dvnode = AFS_FS_I(dir); + struct afs_fid fid = {}; struct inode *inode; struct dentry *d; struct key *key; @@ -957,15 +958,16 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, dentry->d_fsdata (void *)(unsigned long)dvnode->status.data_version; } + + if (!IS_ERR_OR_NULL(inode)) + fid = AFS_FS_I(inode)->fid; + d = d_splice_alias(inode, dentry); if (!IS_ERR_OR_NULL(d)) { d->d_fsdata = dentry->d_fsdata; - trace_afs_lookup(dvnode, &d->d_name, - inode ? AFS_FS_I(inode) : NULL); + trace_afs_lookup(dvnode, &d->d_name, &fid); } else { - trace_afs_lookup(dvnode, &dentry->d_name, - IS_ERR_OR_NULL(inode) ? NULL - : AFS_FS_I(inode)); + trace_afs_lookup(dvnode, &dentry->d_name, &fid); } return d; } diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h index d5ec4fac82ae..564ba1b5cf57 100644 --- a/include/trace/events/afs.h +++ b/include/trace/events/afs.h @@ -915,9 +915,9 @@ TRACE_EVENT(afs_call_state, TRACE_EVENT(afs_lookup, TP_PROTO(struct afs_vnode *dvnode, const struct qstr *name, - struct afs_vnode *vnode), + struct afs_fid *fid), - TP_ARGS(dvnode, name, vnode), + TP_ARGS(dvnode, name, fid), TP_STRUCT__entry( __field_struct(struct afs_fid, dfid ) @@ -928,13 +928,7 @@ TRACE_EVENT(afs_lookup, TP_fast_assign( int __len = min_t(int, name->len, 23); __entry->dfid = dvnode->fid; - if (vnode) { - __entry->fid = vnode->fid; - } else { - __entry->fid.vid = 0; - __entry->fid.vnode = 0; - __entry->fid.unique = 0; - } + __entry->fid = *fid; memcpy(__entry->name, name->name, __len); __entry->name[__len] = 0; ), From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4AE9BC2D0DC for ; Tue, 31 Dec 2019 15:25:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1AD66205ED for ; Tue, 31 Dec 2019 15:25:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MUi/Z6Ec" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727120AbfLaPZE (ORCPT ); Tue, 31 Dec 2019 10:25:04 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:44361 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726659AbfLaPZD (ORCPT ); Tue, 31 Dec 2019 10:25:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1577805902; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=PbZ2iYquyHL3/ESJhoyXhT4LrB0J4rJjHgCtbtkH6oU=; b=MUi/Z6EcDQ6BnRJNnyW8/43MOaWp43nL5W0Je5NayqDOTWLQyXPRrcUJABJAHDwWZLz2ST UcmofnnVlTO1Kl696cYPuJ6S5BZBaYb4LxFtcdil5aeEKhT+lK7SAtljsOR9B3AG3d4FGA hoBKs+szk1EZCs70651pkxfMqca1Tcw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-239-rr9HIQspOn-0-B7a57xWlQ-1; Tue, 31 Dec 2019 10:24:58 -0500 X-MC-Unique: rr9HIQspOn-0-B7a57xWlQ-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3BDF21883520; Tue, 31 Dec 2019 15:24:57 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-52.rdu2.redhat.com [10.10.120.52]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1A20381E35; Tue, 31 Dec 2019 15:24:55 +0000 (UTC) Organization: Red Hat UK Ltd. 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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 2/3] afs: Fix use-after-loss-of-ref From: David Howells To: linux-afs@lists.infradead.org Cc: Al Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, keyrings@vger.kernel.org, dhowells@redhat.com Date: Tue, 31 Dec 2019 15:24:55 +0000 Message-ID: <157780589537.25571.1965637589354532477.stgit@warthog.procyon.org.uk> In-Reply-To: <157780588822.25571.7926816048227538205.stgit@warthog.procyon.org.uk> References: <157780588822.25571.7926816048227538205.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org afs_lookup() has a tracepoint to indicate the outcome of d_splice_alias(), passing it the inode to retrieve the fid from. However, the function gave up its ref on that inode when it called d_splice_alias(), which may have failed and dropped the inode. Fix this by caching the fid. Fixes: 80548b03991f ("afs: Add more tracepoints") Reported-by: Al Viro Signed-off-by: David Howells --- fs/afs/dir.c | 12 +++++++----- include/trace/events/afs.h | 12 +++--------- 2 files changed, 10 insertions(+), 14 deletions(-) diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 497f979018c2..813db1708494 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -908,6 +908,7 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { struct afs_vnode *dvnode = AFS_FS_I(dir); + struct afs_fid fid = {}; struct inode *inode; struct dentry *d; struct key *key; @@ -957,15 +958,16 @@ static struct dentry *afs_lookup(struct inode *dir, struct dentry *dentry, dentry->d_fsdata = (void *)(unsigned long)dvnode->status.data_version; } + + if (!IS_ERR_OR_NULL(inode)) + fid = AFS_FS_I(inode)->fid; + d = d_splice_alias(inode, dentry); if (!IS_ERR_OR_NULL(d)) { d->d_fsdata = dentry->d_fsdata; - trace_afs_lookup(dvnode, &d->d_name, - inode ? AFS_FS_I(inode) : NULL); + trace_afs_lookup(dvnode, &d->d_name, &fid); } else { - trace_afs_lookup(dvnode, &dentry->d_name, - IS_ERR_OR_NULL(inode) ? NULL - : AFS_FS_I(inode)); + trace_afs_lookup(dvnode, &dentry->d_name, &fid); } return d; } diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h index d5ec4fac82ae..564ba1b5cf57 100644 --- a/include/trace/events/afs.h +++ b/include/trace/events/afs.h @@ -915,9 +915,9 @@ TRACE_EVENT(afs_call_state, TRACE_EVENT(afs_lookup, TP_PROTO(struct afs_vnode *dvnode, const struct qstr *name, - struct afs_vnode *vnode), + struct afs_fid *fid), - TP_ARGS(dvnode, name, vnode), + TP_ARGS(dvnode, name, fid), TP_STRUCT__entry( __field_struct(struct afs_fid, dfid ) @@ -928,13 +928,7 @@ TRACE_EVENT(afs_lookup, TP_fast_assign( int __len = min_t(int, name->len, 23); __entry->dfid = dvnode->fid; - if (vnode) { - __entry->fid = vnode->fid; - } else { - __entry->fid.vid = 0; - __entry->fid.vnode = 0; - __entry->fid.unique = 0; - } + __entry->fid = *fid; memcpy(__entry->name, name->name, __len); __entry->name[__len] = 0; ),