From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Date: Tue, 30 Jun 2009 18:41:23 +0000 (-0700)
Subject: elf: limit max map count to safe value
X-Git-Tag: v2.6.31-rc2~53
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=341c87bf346f57748230628c5ad6ee69219250e8;p=pandora-kernel.git

elf: limit max map count to safe value

With ELF, at generating coredump, some more headers other than used
vmas are added.

When max_map_count == 65536, a core generated by following kinds of
code can be unreadable because the number of ELF's program header is
written in 16bit in Ehdr (please see elf.h) and the number overflows.

==
	... = mmap(); (munmap, mprotect, etc...)
	if (failed)
		abort();
==

This can happen in mmap/munmap/mprotect/etc...which calls split_vma().

I think 65536 is not safe as _default_ and reduce it to 65530 is good
for avoiding unexpected corrupted core.

Anyway, max_map_count can be enlarged by sysctl if a user is brave..

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Jakub Jelinek <jakub@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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