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=-6.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 18A32C43381 for ; Mon, 18 Feb 2019 14:39:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DC96721736 for ; Mon, 18 Feb 2019 14:39:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550500771; bh=K8d7LfGfXhNzhU4dsTM6z6d7MbZtdb0zJyLPccE41Qc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=uXKn5M0UBxuy4OX2YBP/d6EVulGKYJrSqokE7oqcxX/ohbfcLnvsPfxx5ErL0rLTK JZJ8pl2uvIwNzRxKv+UBbkPQQIQ9jMLwp8VvNYzalbfU0lhuPC84gIh6YJcbECOAVu EmIN03xCxOabsfBK+uETGXCbwnrpVTv9x5lXgMuM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732849AbfBRNxG (ORCPT ); Mon, 18 Feb 2019 08:53:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:32776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732875AbfBRNxG (ORCPT ); Mon, 18 Feb 2019 08:53:06 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 BD75720449; Mon, 18 Feb 2019 13:53:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550497985; bh=K8d7LfGfXhNzhU4dsTM6z6d7MbZtdb0zJyLPccE41Qc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DYSZ/YpZiwBKeqNlllvg7zzhTiqFwnV4wV+DLbXqmCJA2cP10H4Sr4IGdZO3L28HS mGBAb7iSjw0m5wQTxZrZ9Luxwp2df1Ug0DMcof5m1coUVCYjd+Rlqhbc2bDScodLYS jUIeDpAqnPcg5VkcgHwND0Ob4YipxazHOWkbd45Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ingo Molnar , Masami Hiramatsu , Andreas Ziegler , "Steven Rostedt (VMware)" Subject: [PATCH 4.19 73/85] tracing/uprobes: Fix output for multiple string arguments Date: Mon, 18 Feb 2019 14:43:39 +0100 Message-Id: <20190218133506.940076780@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190218133459.758004711@linuxfoundation.org> References: <20190218133459.758004711@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andreas Ziegler commit 0722069a5374b904ec1a67f91249f90e1cfae259 upstream. When printing multiple uprobe arguments as strings the output for the earlier arguments would also include all later string arguments. This is best explained in an example: Consider adding a uprobe to a function receiving two strings as parameters which is at offset 0xa0 in strlib.so and we want to print both parameters when the uprobe is hit (on x86_64): $ echo 'p:func /lib/strlib.so:0xa0 +0(%di):string +0(%si):string' > \ /sys/kernel/debug/tracing/uprobe_events When the function is called as func("foo", "bar") and we hit the probe, the trace file shows a line like the following: [...] func: (0x7f7e683706a0) arg1="foobar" arg2="bar" Note the extra "bar" printed as part of arg1. This behaviour stacks up for additional string arguments. The strings are stored in a dynamically growing part of the uprobe buffer by fetch_store_string() after copying them from userspace via strncpy_from_user(). The return value of strncpy_from_user() is then directly used as the required size for the string. However, this does not take the terminating null byte into account as the documentation for strncpy_from_user() cleary states that it "[...] returns the length of the string (not including the trailing NUL)" even though the null byte will be copied to the destination. Therefore, subsequent calls to fetch_store_string() will overwrite the terminating null byte of the most recently fetched string with the first character of the current string, leading to the "accumulation" of strings in earlier arguments in the output. Fix this by incrementing the return value of strncpy_from_user() by one if we did not hit the maximum buffer size. Link: http://lkml.kernel.org/r/20190116141629.5752-1-andreas.ziegler@fau.de Cc: Ingo Molnar Cc: stable@vger.kernel.org Fixes: 5baaa59ef09e ("tracing/probes: Implement 'memory' fetch method for uprobes") Acked-by: Masami Hiramatsu Signed-off-by: Andreas Ziegler Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Masami Hiramatsu Signed-off-by: Greg Kroah-Hartman --- kernel/trace/trace_uprobe.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -141,7 +141,14 @@ static void FETCH_FUNC_NAME(memory, stri ret = strncpy_from_user(dst, src, maxlen); if (ret == maxlen) - dst[--ret] = '\0'; + dst[ret - 1] = '\0'; + else if (ret >= 0) + /* + * Include the terminating null byte. In this case it + * was copied by strncpy_from_user but not accounted + * for in ret. + */ + ret++; if (ret < 0) { /* Failed to fetch string */ ((u8 *)get_rloc_data(dest))[0] = '\0';