Re: [PATCH bpf v2 1/2] bpf: Fix bpf_dynptr_copy() for overlapping ranges in one packet

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] bpf: non-standard multi-line comment style in bpf_dynptr_copy()
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commit 4a57e7196e830451e2770433571b9c37faffc18b
Author: Ayushman Rout <ayushmanrout27@gmail.com>

bpf: Fix bpf_dynptr_copy() for overlapping ranges in one packet

This commit fixes overlapping copies within the same packet in
bpf_dynptr_copy() by avoiding direct slice buffers when both dynptrs share the
same underlying data and copying chunks in reverse when the destination is
above the source.

> diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
> index 648abe1ba63ae..b74c03669b5fd 100644
> --- a/kernel/bpf/helpers.c
> +++ b/kernel/bpf/helpers.c
> @@ -3291,8 +3291,10 @@ __bpf_kfunc int bpf_dynptr_copy(const struct bpf_dynptr *dst_ptr, u64 dst_off,
>  {
>  	const struct bpf_dynptr_kern *dst = (struct bpf_dynptr_kern *)dst_ptr;
>  	const struct bpf_dynptr_kern *src = (struct bpf_dynptr_kern *)src_ptr;
> +	bool same = src->data == dst->data;
>  	void *src_slice, *dst_slice;
>  	char buf[256];
> +	bool rev;
>  	u64 off;
>  
>  	src_slice = bpf_dynptr_slice(src_ptr, src_off, NULL, size);
> @@ -3303,25 +3305,31 @@ __bpf_kfunc int bpf_dynptr_copy(const struct bpf_dynptr *dst_ptr, u64 dst_off,
>  		return 0;
>  	}
>  
> -	if (src_slice)
> +	/* The other range is copied piece by piece. A slice of the same packet
> +	 * may overlap with it, so it cannot be the buffer for that.
> +	 */

[Severity: Low]
This isn't a bug, but in bpf_dynptr_copy() in kernel/bpf/helpers.c, could this
new multi-line comment follow the BPF subsystem comment style with the opening
/* on its own line:

	/*
	 * The other range is copied piece by piece. A slice of the same packet
	 * may overlap with it, so it cannot be the buffer for that.
	 */

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Sashiko AI review · https://sashiko.dev/#/patchset/20261026162810.12862-1-ayushmanrout27@gmail.com?part=1