Re: [PATCH 2/2] ARM: fix framepointer check in unwind_frame

[Jean Pihet]

On 5 December 2013 09:34, Konstantin Khlebnikov
<k.khlebnikov@xxxxxxxxxxx> wrote:
> This patch fixes corner case when (fp + 4) overflows unsigned long,
> for example: fp = 0xFFFFFFFF -> fp + 4 == 3.
>
> Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@xxxxxxxxxxx>
> ---
>  arch/arm/kernel/stacktrace.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/kernel/stacktrace.c b/arch/arm/kernel/stacktrace.c
> index 00f79e5..af4e8c8 100644
> --- a/arch/arm/kernel/stacktrace.c
> +++ b/arch/arm/kernel/stacktrace.c
> @@ -31,7 +31,7 @@ int notrace unwind_frame(struct stackframe *frame)
>         high = ALIGN(low, THREAD_SIZE);
>
>         /* check current frame pointer is within bounds */
> -       if (fp < (low + 12) || fp + 4 >= high)
> +       if (fp < low + 12 || fp > high - 4)
Shouldn't that use the '>=' comparison?

Jean
>                 return -EINVAL;
>
>         /* restore the registers from the stack frame */
>
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