From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/11654 Path: news.gmane.org!.POSTED!not-for-mail From: Alexander Monakov Newsgroups: gmane.linux.lib.musl.general Subject: Re: [PATCH] fix undefined behavior in ptrace Date: Wed, 5 Jul 2017 00:51:05 +0300 (MSK) Message-ID: References: <20170628132513.15483-1-amonakov@ispras.ru> <20170628151328.GD1627@brightrain.aerifal.cx> <20170704211058.GO1627@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Trace: blaine.gmane.org 1499205083 14849 195.159.176.226 (4 Jul 2017 21:51:23 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 4 Jul 2017 21:51:23 +0000 (UTC) User-Agent: Alpine 2.20.13 (LNX 116 2015-12-14) To: musl@lists.openwall.com Original-X-From: musl-return-11667-gllmg-musl=m.gmane.org@lists.openwall.com Tue Jul 04 23:51:20 2017 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by blaine.gmane.org with smtp (Exim 4.84_2) (envelope-from ) id 1dSVj3-0003Zl-Ay for gllmg-musl@m.gmane.org; Tue, 04 Jul 2017 23:51:17 +0200 Original-Received: (qmail 32312 invoked by uid 550); 4 Jul 2017 21:51:21 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Original-Received: (qmail 32288 invoked from network); 4 Jul 2017 21:51:20 -0000 In-Reply-To: <20170704211058.GO1627@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:11654 Archived-At: --- On Tue, 4 Jul 2017, Rich Felker wrote: > Thoughts? I'm not convinced it's a good idea, given that it's a Linux specific interface, and the manpage rather explicitly discourages passing fewer than four arguments. Plus, handling SPARC-specific differences of argument counts for PTRACE_{GET,SET}{FP,}REGS would be annoying. What makes sense is to retrieve the fifth argument only when needed: src/linux/ptrace.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/src/linux/ptrace.c b/src/linux/ptrace.c index 83b8022b..a3f393d9 100644 --- a/src/linux/ptrace.c +++ b/src/linux/ptrace.c @@ -7,14 +7,18 @@ long ptrace(int req, ...) { va_list ap; pid_t pid; - void *addr, *data, *addr2; + void *addr, *data, *addr2 = 0; long ret, result; va_start(ap, req); pid = va_arg(ap, pid_t); addr = va_arg(ap, void *); data = va_arg(ap, void *); - addr2 = va_arg(ap, void *); + /* PTRACE_{READ,WRITE}{DATA,TEXT} (16...19) are specific to SPARC. */ +#ifdef PTRACE_READDATA + if ((unsigned)req - PTRACE_READDATA < 4) + addr2 = va_arg(ap, void *); +#endif va_end(ap); if (req-1U < 3) data = &result; -- 2.11.0