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Message-ID: <20140627004637.GA538@muslin>
Date: Thu, 26 Jun 2014 17:46:38 -0700
From: Isaac Dunham <ibid.ag@...il.com>
To: musl@...ts.openwall.com
Subject: Re: ELF loader rejects older glibc binary
On Thu, Jun 26, 2014 at 10:50:08AM +0300, Timo Teras wrote:
> On Wed, 25 Jun 2014 20:59:24 -0700
> Isaac Dunham <ibid.ag@...il.com> wrote:
> > The drivers in question may be found here:
> > http://support.brother.com/g/b/downloadlist.aspx?c=us&lang=en&prod=dcp7065dn_all&os=128
> >
> > I grabbed the "LPR printer driver".
> > After extracting it (ar x dcp7065*deb; tar xvzf data.tar.gz),
> > I found the binaries in
> > usr/local/Brother/Printer/DCP7065DN/{inf,lpd}/;
> > the one I'd suggest poking at first is
> > "usr/local/Brother/Printer/DCP7065DN/lpd/rawtobr3" (I previously
> > determined that rawtobr3 does all the conversions).
> > After locating the binaries and verifying with file that they were
> > dynamically linked ELF binaries, I ran ldd.
> > When this failed with the message:
> > ldd: rawtobr3: Not a valid dynamic program
> > I then ran "strace ldd rawtobr3"; the output indicates that musl
> > mmap'd it and failed without trying to run it:
> >
> > ---start strace output---
> > execve("/usr/bin/ldd", ["ldd", "rawtobr3"], [/* 19 vars */]) = 0
> > open("rawtobr3", O_RDONLY|O_LARGEFILE) = 3
> > read(3,
> > "\177ELF\1\1\1\0\0\0\0\0\0\0\0\0\2\0\3\0\1\0\0\0\324\207\4\0104\0\0\0"...,
> > 936) = 936 mmap2(0x8048000, 49152, PROT_READ|PROT_EXEC, MAP_PRIVATE,
> > 3, 0) = 0x566f1000 munmap(0x566f1000, 49152) = 0
> > writev(2, [{"ldd: rawtobr3: Not a valid dynam"..., 43}, {NULL, 0}],
> > 2ldd: rawtobr3: Not a valid dynamic program ) = 43
> > exit_group(1) = ? +++ exited with 1 +++
> > ---end strace output---
> >
> > strings suggests that it expects glibc 2.1 ABI, and that almost all
> > the symbol requirements are met (_IO_stdin_used being the possible
> > exception).
>
> Do note that Alpine Linux runs grsec which includes PaX features. One
> is that text relocations are disabled by default.
>
> Try first:
> paxctl -c -pem /path/to/rawtobr3
>
> if it makes any difference.
Thanks for mentioning that; I've just tested on my other musl system,
and it's definitely a kernel difference (it runs on a non-pax system.)
That said, paxctl didn't make a difference.
Thanks,
Isaac Dunham
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