Bug#843128: partially solved

From	Didier 'OdyX' Raboud <odyx@debian.org>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#843128: partially solved
Date	2016-12-19 12:20 +0100
Message-ID	<sQ493-70A-7@gated-at.bofh.it> (permalink)
References	<sMkYN-75X-3@gated-at.bofh.it> <sMkYN-75X-1@gated-at.bofh.it> <sMt61-3Ds-17@gated-at.bofh.it>
Organization	Debian - The Universal OS

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Control: found -1 4.8.11-1

Le vendredi, 9 décembre 2016, 13.03:44 h CET Ben Hutchings a écrit :
> fgetty uses dietlibc, and the stable version of dietlibc still uses the
> vsyscall feature which is now disabled by default.  You can make it
> work again by adding 'vsyscall=emulate' to the kernel command line.
> 
> I'll have to reconsider whether to revert the configuration change now
> that I know dietlibc is a problem.

On a vagrant-lxc setup using Liip's drifter [0], we see two different programs 
segfaulting immediately after a vsyscall entry in syslog:

Dec 19 10:07:55 gyllingar kernel: [  834.998381] logsave[12259] vsyscall 
attempted with vsyscall=none ip:ffffffffff600400 cs:33 sp:7ffc918c1fc8 
ax:ffffffffff600400 si:4017c1 di:0
Dec 19 10:07:55 gyllingar kernel: [  834.998384] logsave[12259]: segfault at 
ffffffffff600400 ip ffffffffff600400 sp 00007ffc918c1fc8 error 15
Dec 19 10:07:55 gyllingar kernel: [  834.998934] ip[12261] vsyscall attempted 
with vsyscall=none ip:ffffffffff600400 cs:33 sp:7fff467d8d18 
ax:ffffffffff600400 si:433d2f di:0
Dec 19 10:07:55 gyllingar kernel: [  834.998936] ip[12261]: segfault at 
ffffffffff600400 ip ffffffffff600400 sp 00007fff467d8d18 error 15

So apparently /sbin/logsave from src:e2fsprogs and /sbin/ip from src:iproute2 
have the same problem. And this was on linux-image-4.8.0-2-amd64 4.8.11-1.

Both problems are circumvented by booting with vsyscall=emulated on the kernel 
command line.

Cheers,
OdyX

[0] https://github.com/liip/drifter

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Bug#843128: partially solved Ricardo Fabian Peliquero <zhana@lasampa.com.ar> - 2016-12-09 05:30 +0100
  Bug#843128: partially solved Ben Hutchings <ben@decadent.org.uk> - 2016-12-09 14:10 +0100
    Bug#843128: partially solved Ricardo Fabian Peliquero <zhana@lasampa.com.ar> - 2016-12-09 17:40 +0100
    Bug#843128: partially solved Didier 'OdyX' Raboud <odyx@debian.org> - 2016-12-19 12:20 +0100

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