Messages in this thread Patch in this message | | | Date | Mon, 12 Jan 2009 15:10:29 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH]Fix: 32bit binary has 64bit address of stack vma |
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On Mon, 12 Jan 2009 15:05:51 -0800 Mike Waychison <mikew@google.com> wrote:
> > Subject: fs/exec.c: fix value of vma->vm_pgoff for the stack VMA of 32-bit processes > > From: Ying Han <yinghan@google.com> > > > > With a 32 bit binary running on a 64 bit system, the /proc/pid/maps for > > the [stack] VMA displays a 64-bit address: > > > > ff96c000-ff981000 rwxp 7ffffffea000 00:00 0 [stack] > > > > This is because vma->vm_pgoff for that VMA is incorrectly being stored in > > units of offset-in-bytes. It should be stored in units of offset-in-pages. > > > > The problem is that the offset was stored without taking into account > the shift.
Sigh. Is it efficient to have me sitting here reverse-engineering the code, writing your changelog?
From: Ying Han <yinghan@google.com>
With a 32 bit binary running on a 64 bit system, the /proc/pid/maps for the [stack] VMA displays a 64-bit address:
ff96c000-ff981000 rwxp 7ffffffea000 00:00 0 [stack]
This is because vma->vm_pgoff for that VMA is not being updated for the shift of the stack VMA.
Signed-off-by: Ying Han <yinghan@google.com> Cc: Mike Waychison <mikew@google.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---
fs/exec.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff -puN fs/exec.c~fs-execc-fix-value-of-vma-vm_pgoff-for-the-stack-vma-of-32-bit-processes fs/exec.c --- a/fs/exec.c~fs-execc-fix-value-of-vma-vm_pgoff-for-the-stack-vma-of-32-bit-processes +++ a/fs/exec.c @@ -509,6 +509,7 @@ static int shift_arg_pages(struct vm_are unsigned long length = old_end - old_start; unsigned long new_start = old_start - shift; unsigned long new_end = old_end - shift; + unsigned long new_pgoff = new_start >> PAGE_SHIFT; struct mmu_gather *tlb; BUG_ON(new_start > new_end); @@ -523,7 +524,7 @@ static int shift_arg_pages(struct vm_are /* * cover the whole range: [new_start, old_end) */ - vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL); + vma_adjust(vma, new_start, old_end, new_pgoff, NULL); /* * move the page tables downwards, on failure we rely on @@ -556,7 +557,7 @@ static int shift_arg_pages(struct vm_are /* * shrink the vma to just the new range. */ - vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL); + vma_adjust(vma, new_start, new_end, new_pgoff, NULL); return 0; } _
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