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| author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2009-06-30 11:41:23 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-06-30 18:55:59 -0700 |
| commit | 341c87bf346f57748230628c5ad6ee69219250e8 (patch) | |
| tree | 93937b91c3680127e38a310d5679b9ca84067b04 /fs/binfmt_elf.c | |
| parent | b1cfebc9231a69d46d66982a2c856ba41ef6d6b9 (diff) | |
| download | linux-341c87bf346f57748230628c5ad6ee69219250e8.tar.gz linux-341c87bf346f57748230628c5ad6ee69219250e8.tar.bz2 linux-341c87bf346f57748230628c5ad6ee69219250e8.zip | |
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>
Diffstat (limited to 'fs/binfmt_elf.c')
| -rw-r--r-- | fs/binfmt_elf.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 9fa212b014a5..f1867900e459 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1929,7 +1929,10 @@ static int elf_core_dump(long signr, struct pt_regs *regs, struct file *file, un elf = kmalloc(sizeof(*elf), GFP_KERNEL); if (!elf) goto out; - + /* + * The number of segs are recored into ELF header as 16bit value. + * Please check DEFAULT_MAX_MAP_COUNT definition when you modify here. + */ segs = current->mm->map_count; #ifdef ELF_CORE_EXTRA_PHDRS segs += ELF_CORE_EXTRA_PHDRS; |