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author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2009-06-30 11:41:23 -0700 |
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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 |
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; |