RE: [PATCH 1/2] setup_arg_pages can insert overlapping vma

From: Zou, Nanhai <>
Date: 2004-11-25 11:44:06
> -----Original Message-----
> From: Hugh Dickins []
> Sent: Thursday, November 25, 2004 12:31 AM
> To: Zou, Nanhai
> Cc: Chris Wright; Andrew Morton; Linus Torvalds; Luck, Tony; Martin
> Andi Kleen;;
> Subject: RE: [PATCH 1/2] setup_arg_pages can insert overlapping vma
> Thanks a lot for taking this further.
> Yes, I agree, that's a welcome improvement.  I'm surprised if all
> those ia64_elf32_init checks are necessary, but better safe than
> Something crosses my mind, you'll know better than I: is it possible
> construct ELFs or A.OUTs which would need the check in
> to be even more defensive?  That is, should it also be checking that
> vma->vm_end > vma->vm_start (vma being the one to be inserted)?
> Or that vma->vm_end <= TASK_SIZE?  If I remember rightly, a 0-length
> vma can cause confusion but survive quite well until exit_mmap's
> BUG_ON(mm->map_count).
  Since all elf and a.out sections are inserted with do_mmap which takes
start_addr and an unsigned length as parameters. And do_mmap also check
for zero lenth mapping.
I think we could not have vma with (vma->vm_end <= vm->vm_start) by
construct a bad binary executable.

Zou Nan hai 
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Received on Wed Nov 24 21:46:30 2004

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