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Subject: |
24.0.95; Segfault in unexec on Linux 3.3* with grsecurity/PaX |
|
Date: |
Thu, 3 May 2012 11:12:00 +0200 |
Forwarding downstream bug <https://bugs.gentoo.org/411439>.
Emacs 23.4 and 24.0.95 both fail to build on a Gentoo system with a
sys-kernel/hardened-sources-3.3* kernel, i.e. Linux 3.3* with the
grsecurity/PaX patches from <http://grsecurity.net/>
(e.g., grsecurity-2.9-3.3.4-201204272006.patch).
Dumping under the name emacs
**************************************************
Warning: Your system has a gap between BSS and the
heap (15045480 bytes). This usually means that exec-shield
or something similar is in effect. The dump may
fail because of this. See the section about
exec-shield in etc/PROBLEMS for more information.
**************************************************
make[1]: *** [bootstrap-emacs] Segmentation fault
make[1]: Leaving directory
`/var/tmp/portage/app-editors/emacs-23.4-r1/work/emacs-23.4/src'
make: *** [src] Error 2
Since it still could be successfully built with hardened-sources-3.2*,
we had first reported this problem to grsecurity/PaX upstream.
However, they claim that it is due to a bug in Emacs' unexec code.
Quoting from <https://bugs.gentoo.org/show_bug.cgi?id=411439#c13> and
following comments:
| i've debugged the problem and it's a bug in emacs. it wants to create
| a memory dump of its address space without actually looking at what
| memory ranges are available with what access rights. due to recentish
| changes in PaX the gap between the end of the main executable's data
| section and the start of the brk heap is mapped with PROT_NONE rights,
| so no access is allowed and this is where emacs fails.
| ADDR_NO_RANDOMIZE was added as a workaround to fix userland bugs
| like what emacs has (the first bug is about assuming a particular
| address space layout that no standard has ever guaranteed, the
| second bug is that emacs doesn't use the kernel provided interface
| to discover its own address space layout).
| [...] fundamentally a bug in emacs's memory dumper code, the proper
| fix should be in there.
Could GNU Emacs upstream comment on this, please?
Ulrich
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--- Begin Message ---
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Subject: |
Re: bug#11398: 24.0.95; Segfault in unexec on Linux 3.3* with grsecurity/PaX |
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Date: |
Wed, 28 Aug 2019 16:27:19 +0200 |
Ulrich Mueller <address@hidden> writes:
> I'd suggest to close this bug. If there are similar problems with the
> portable dumper, it may be cleaner to open a fresh bug for them.
Thanks; closing.
Best regards,
Stefan Kangas
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