[PATCH v2 1/3] arm64: check for number of arguments in syscall_get/set_arguments()

[Will Deacon]

On Thu, Oct 03, 2013 at 06:47:44AM +0100, AKASHI Takahiro wrote:
> In ftrace_syscall_enter(),
>     syscall_get_arguments(..., 0, n, ...)
>         if (i == 0) { <handle orig_x0> ...; n--;}
>         memcpy(..., n * sizeof(args[0]));
> If 'number of arguments(n)' is zero and 'argument index(i)' is also zero in
> syscall_get_arguments(), none of arguments should be copied by memcpy().
> Otherwise 'n--' can be a big positive number and unexpected amount of data
> will be copied. Tracing system calls which take no argument, say sync(void),
> may hit this case and eventually make the system corrupted.
> This patch fixes the issue both in syscall_get_arguments() and
> syscall_set_arguments().
> 
> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>

Acked-by: Will Deacon <will.deacon at arm.com>

Cheers,

Will