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[209.132.180.67]) by mx.google.com with ESMTP id f129si1060001oia.243.2020.04.01.09.44.56; Wed, 01 Apr 2020 09:45:08 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=H1muohoG; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389511AbgDAQnu (ORCPT + 99 others); Wed, 1 Apr 2020 12:43:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:44700 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732793AbgDAQnt (ORCPT ); Wed, 1 Apr 2020 12:43:49 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9E3732063A; Wed, 1 Apr 2020 16:43:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585759429; bh=GToXniXT+TcobdymTSjFYMLoF1tRlgZ/NIKKH8vjf6Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=H1muohoGadTXyeSADhBPRKxPcrC1PPFoGASneYb6ZUKNvjORL+lKh71EAB4MnoCla z/gQRhLIZqN4/AdfCE1AX4btJrvLsYcMn0a23o7a5+PKEAVvvJeQT7yUJZ1/IUuCG/ M/fv8skUvb/zANp7RiIgIdVnxat5RMi2qEW4Bucw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vasily Averin , Tejun Heo , Sasha Levin Subject: [PATCH 4.14 074/148] cgroup-v1: cgroup_pidlist_next should update position index Date: Wed, 1 Apr 2020 18:17:46 +0200 Message-Id: <20200401161600.483221116@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200401161552.245876366@linuxfoundation.org> References: <20200401161552.245876366@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vasily Averin [ Upstream commit db8dd9697238be70a6b4f9d0284cd89f59c0e070 ] if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. # mount | grep cgroup # dd if=/mnt/cgroup.procs bs=1 # normal output ... 1294 1295 1296 1304 1382 584+0 records in 584+0 records out 584 bytes copied dd: /mnt/cgroup.procs: cannot skip to specified offset 83 <<< generates end of last line 1383 <<< ... and whole last line once again 0+1 records in 0+1 records out 8 bytes copied dd: /mnt/cgroup.procs: cannot skip to specified offset 1386 <<< generates last line anyway 0+1 records in 0+1 records out 5 bytes copied https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin --- kernel/cgroup/cgroup-v1.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index a2c05d2476ac5..d148965180893 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -501,6 +501,7 @@ static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos) */ p++; if (p >= end) { + (*pos)++; return NULL; } else { *pos = *p; -- 2.20.1