On Sun, Aug 05, 2007 at 09:03:23PM -0500, Dave Boutcher wrote:
>
> /proc/pid/pagemap has a header (usually 8 bytes) the length
> of which needs to be compensated for when converting from
> proc file offset to page number. The calculation of the
> starting page number (svpfn) compensates for this, but the
> calculation of the ending page number (evpfn) does not, resulting
> in reads returning 8 bytes more than were asked for and
> nastily overwriting userspace memory.
Does this mean you're running on a 64-bit arch? I'd already fixed this
locally, but it was off by 4 for me.
Acked-by: Matt Mackall <[email protected]>
> Diffed against 2.6.23-rc1-mm2
>
> Signed-off-by: Dave Boutcher <[email protected]>
> ---
> fs/proc/task_mmu.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 4594f15..b2baeab 100644
> --- a/fs/proc/task_mmu.c
> +++ b/fs/proc/task_mmu.c
> @@ -627,7 +627,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
> addr = PAGE_SIZE * svpfn;
> if ((svpfn + 1) * sizeof(unsigned long) != src)
> goto out;
> - evpfn = min((src + count) / sizeof(unsigned long),
> + evpfn = min((src + count) / sizeof(unsigned long) - 1,
> ((~0UL) >> PAGE_SHIFT) + 1);
> count = (evpfn - svpfn) * sizeof(unsigned long);
> end = PAGE_SIZE * evpfn;
> --
> 1.4.4.2
--
Mathematics is the supreme nostalgia of our time.
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