Re: [PATCH] perf_counter: fix buffer overflow in perf_copy_attr()

[Paul Mackerras]

Xiao Guangrong writes:

> If we pass a big size data over perf_counter_open syscall, the kernel
> will copy this data to a small buffer, It will cause kernel crash.
> 
> This bug make kernel unsafe and no-root user can trigger it.
> 
> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
> ---
>  kernel/perf_counter.c |    1 +
>  1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
> index 667ab25..75c46c0 100644
> --- a/kernel/perf_counter.c
> +++ b/kernel/perf_counter.c
> @@ -4216,6 +4216,7 @@ static int perf_copy_attr(struct perf_counter_attr __user *uattr,
>  			if (val)
>  				goto err_size;
>  		}
> +		size = sizeof(*attr);

Looks right to me.

Acked-by: Paul Mackerras <paulus@xxxxxxxxx>
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