From nobody Thu Apr 30 08:30:37 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0E9BC433F5 for ; Tue, 31 May 2022 08:30:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244878AbiEaIav (ORCPT ); Tue, 31 May 2022 04:30:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244867AbiEaIas (ORCPT ); Tue, 31 May 2022 04:30:48 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 1F6E762137 for ; Tue, 31 May 2022 01:30:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1653985846; 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; bh=dejbYOzfjKF6dMJXhvNBnCnEVYYCsLU8eaE5kLKtEMo=; b=WvwJPdx/xVw36jL3nx9o9TI5Rhw5CaFC7qN1t3WAaZEPivQ3lzucDcCLOTXL8KMpwM96fc r9mHRbyKgy2JL8ARh+1RCkZWCajdW5bRRhcLYzD79f2Ym0xzGUbHTq1I1xQ1nHZSS9CCP5 dPrj4z1VIkI6+TQTVpEyqcv7NVhZzC4= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-436-Ej6uU4mePMuU1vbZOWgMYQ-1; Tue, 31 May 2022 04:30:42 -0400 X-MC-Unique: Ej6uU4mePMuU1vbZOWgMYQ-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3BDC63C11052; Tue, 31 May 2022 08:30:42 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.33.36.8]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5DFBB492C3B; Tue, 31 May 2022 08:30:41 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH] afs: Fix infinite loop found by xfstest generic/676 From: David Howells To: torvalds@linux-foundation.org Cc: Marc Dionne , Marc Dionne , linux-afs@lists.infradead.org, dhowells@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 31 May 2022 09:30:40 +0100 Message-ID: <165398584061.263049.2347678478539579934.stgit@warthog.procyon.org.uk> User-Agent: StGit/1.4 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In AFS, a directory is handled as a file that the client downloads and parses locally for the purposes of performing lookup and getdents operations. The in-kernel afs filesystem has a number of functions that do this. A directory file is arranged as a series of 2K blocks divided into 32-byte slots, where a directory entry occupies one or more slots, plus each block starts with one or more metadata blocks. When parsing a block, if the last slots are occupied by a dirent that occupies more than a single slot and the file position points at a slot that's not the initial one, the logic in afs_dir_iterate_block() that skips over it won't advance the file pointer to the end of it. This will cause an infinite loop in getdents() as it will keep retrying that block and failing to advance beyond the final entry. Fix this by advancing the file pointer if the next entry will be beyond it when we skip a block. This was found by the generic/676 xfstest but can also be triggered with something like: ~/xfstests-dev/src/t_readdir_3 /xfstest.test/z 4000 1 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: David Howells Reviewed-by: Marc Dionne Tested-by: Marc Dionne cc: linux-afs@lists.infradead.org Link: http://lore.kernel.org/r/165391973497.110268.2939296942213894166.stgi= t@warthog.procyon.org.uk/ --- fs/afs/dir.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/afs/dir.c b/fs/afs/dir.c index 932e61e28e5d..bdac73554e6e 100644 --- a/fs/afs/dir.c +++ b/fs/afs/dir.c @@ -463,8 +463,11 @@ static int afs_dir_iterate_block(struct afs_vnode *dvn= ode, } =20 /* skip if starts before the current position */ - if (offset < curr) + if (offset < curr) { + if (next > curr) + ctx->pos =3D blkoff + next * sizeof(union afs_xdr_dirent); continue; + } =20 /* found the next entry */ if (!dir_emit(ctx, dire->u.name, nlen,