Re: [PATCH bpf-next 2/4] bpf: Use __GFP_NOWARN for kvmalloc_array() when attaching multiple kprobes

[Jiri Olsa <olsajiri@gmail.com>]

On Mon, Dec 11, 2023 at 07:28:41PM +0800, Hou Tao wrote:
> From: Hou Tao <houtao1@huawei.com>
> 
> An abnormally big cnt may also be assigned to kprobe_multi.cnt when
> attaching multiple kprobes. It will trigger the following warning in
> kvmalloc_node():
> 
> 	if (unlikely(size > INT_MAX)) {
> 	    WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> 	    return NULL;
> 	}
> 
> Fix the warning by using __GFP_NOWARN when invoking kvmalloc_array() in
> bpf_kprobe_multi_link_attach().
> 
> Fixes: 0dcac2725406 ("bpf: Add multi kprobe link")
> Signed-off-by: Hou Tao <houtao1@huawei.com>

Acked-by: Jiri Olsa <jolsa@kernel.org>

thanks,
jirka

> ---
>  kernel/trace/bpf_trace.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 07b9b5896d6c..64f200890c19 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -2605,11 +2605,11 @@ static int copy_user_syms(struct user_syms *us, unsigned long __user *usyms, u32
>  	int err = -ENOMEM;
>  	unsigned int i;
>  
> -	syms = kvmalloc_array(cnt, sizeof(*syms), GFP_KERNEL);
> +	syms = kvmalloc_array(cnt, sizeof(*syms), GFP_KERNEL | __GFP_NOWARN);
>  	if (!syms)
>  		goto error;
>  
> -	buf = kvmalloc_array(cnt, KSYM_NAME_LEN, GFP_KERNEL);
> +	buf = kvmalloc_array(cnt, KSYM_NAME_LEN, GFP_KERNEL | __GFP_NOWARN);
>  	if (!buf)
>  		goto error;
>  
> @@ -2972,13 +2972,13 @@ int bpf_kprobe_multi_link_attach(const union bpf_attr *attr, struct bpf_prog *pr
>  		return -EINVAL;
>  
>  	size = cnt * sizeof(*addrs);
> -	addrs = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL);
> +	addrs = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL | __GFP_NOWARN);
>  	if (!addrs)
>  		return -ENOMEM;
>  
>  	ucookies = u64_to_user_ptr(attr->link_create.kprobe_multi.cookies);
>  	if (ucookies) {
> -		cookies = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL);
> +		cookies = kvmalloc_array(cnt, sizeof(*addrs), GFP_KERNEL | __GFP_NOWARN);
>  		if (!cookies) {
>  			err = -ENOMEM;
>  			goto error;
> -- 
> 2.29.2
>