From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/6808 Path: news.gmane.org!not-for-mail From: Rich Felker Newsgroups: gmane.linux.lib.musl.general Subject: Re: musl built with pcc yields segfaults in dynlink.c Date: Tue, 6 Jan 2015 19:53:57 -0500 Message-ID: <20150107005357.GN4574@brightrain.aerifal.cx> References: <20150106074849.GA25889@newbook> <20150106204924.GM4574@brightrain.aerifal.cx> <20150106225647.GA2194@newbook> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Trace: ger.gmane.org 1420592099 28366 80.91.229.3 (7 Jan 2015 00:54:59 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 7 Jan 2015 00:54:59 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-6821-gllmg-musl=m.gmane.org@lists.openwall.com Wed Jan 07 01:54:54 2015 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1Y8et2-0002Cz-PU for gllmg-musl@m.gmane.org; Wed, 07 Jan 2015 01:54:12 +0100 Original-Received: (qmail 9620 invoked by uid 550); 7 Jan 2015 00:54:11 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 9612 invoked from network); 7 Jan 2015 00:54:11 -0000 Content-Disposition: inline In-Reply-To: <20150106225647.GA2194@newbook> User-Agent: Mutt/1.5.21 (2010-09-15) Original-Sender: Rich Felker Xref: news.gmane.org gmane.linux.lib.musl.general:6808 Archived-At: On Tue, Jan 06, 2015 at 02:56:50PM -0800, Isaac Dunham wrote: > On Tue, Jan 06, 2015 at 03:49:24PM -0500, Rich Felker wrote: > > On Mon, Jan 05, 2015 at 11:48:50PM -0800, Isaac Dunham wrote: > > > Hello, > > > I'm trying to get a pcc-built libc.so that works. > > > With the latest PCC, musl builds (lib/libc.so) and the result will display > > > the proper messages if run from the command line without arguments. > > > However, if I try to run a program with it > > > (even via -Wl,-dynamic-linker,`pwd`/lib/libc.so), I get a segfault > > > in src/ldso/dynlink.c: > > > (gdb) where > > > #0 sysv_hash (s0=0x0, s0=0x0) at src/ldso/dynlink.c:177 > > > #1 0xb7f6f747 in find_sym (dso=0xbffffb18, rel=0xb7ffe1d4 <.L1502>, > > > rel_size=, stride=, dso=0xbffffb18, > > > rel=0xb7ffe1d4 <.L1502>, rel_size=, stride=) > > > at src/ldso/dynlink.c:251 > > > #2 0xb7f6f916 in do_relocs () at src/ldso/dynlink.c:308 > > > Backtrace stopped: frame did not save the PC > > > > > > I'm using Alpine Linux edge, recently updated, with linux-vanilla. > > > > It would be helpful to see the readelf -a output for libc.so and the > > binary using it, and whatever information gdb can give on the value of > > local vars at each of the above call frames. > > Attaching a tar.xz containing the output of: > - readelf -a lib/libc.so: libc-pcc.readelf > - readelf -a a.out: argvname.readelf > - echo -e 'run\nwhere\nbt full' |gdb ./a.out: argvname.gdb > (which is substantially similar to the output for "lib/libc.so ./a.out") > - and the source for a.out: argvname.c > > It's 51k, so I'm hoping it gets through. It came through fine, but I suspect the debug info is bogus. The values being shown don't seem to make sense. It might help more to show the disassembly at eip and the value of all registers, or to post the binaries somewhere I could download and analyze them. I looked at the readelf outputs and didn't see any invalid relocs immediately, so I'm not sure what's happening. Rich