Re: [PATCH bpf-next v5 02/10] bpf: mark instructions accessing program stack

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Multi-line comment does not follow the modern kernel/BPF comment style.
--

--- Patch [2]: [PATCH bpf-next v5 02/10] bpf: mark instructions accessing program stack ---
commit 03ab01d124457ab321033266bf176b6f34230aec
Author: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>

bpf: mark instructions accessing program stack

JIT compilers need to know if load/store instructions target the BPF stack to
avoid over-instrumenting them with KASAN checks. This commit makes the
verifier mark instructions accordingly, setting non-stack-access true if any
state leads to an access other than PTR_TO_STACK. It also ensures instruction
patching maintains correct markings.

> diff --git a/kernel/bpf/fixups.c b/kernel/bpf/fixups.c
> index 188ea6205d617..0eda5512baece 100644
> --- a/kernel/bpf/fixups.c
> +++ b/kernel/bpf/fixups.c
[ ... ]
> @@ -172,8 +184,14 @@ static void adjust_insn_aux_data(struct bpf_verifier_env *env,
>  	 */
>  	data[off].zext_dst = insn_has_def32(insn + off + cnt - 1);
>  
> -	if (cnt == 1)
> +	if (cnt == 1) {
> +		/* A non-memory accessing insn could have been replaced by a
> +		 * memory accessing insn, systematically mark it for non-stack
> +		 * access
> +		 */

[Severity: Low]
This isn't a bug, but does this multi-line comment in adjust_insn_aux_data()
follow the preferred BPF subsystem comment style? The BPF guidelines require
the opening /* to be on its own line for multi-line comments.

> +		data[off].non_stack_access = is_mem_insn(insn + off);
>  		return;
> +	}
>  	prog_len = new_prog->len;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260709-kasan-v5-0-1c64af8e4e1e@bootlin.com?part=2