linux-kernel - Re: [PATCH bpf-next v3 1/2] bpf: Allow access to const void pointer arguments in tracing programs

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Message-ID: <CAADnVQLZH-ijYDpHwWGNm858mOLTup2QM_5ZuZwro+HoboeTCg@mail.gmail.com>
Date: Tue, 22 Apr 2025 13:03:01 -0700
From: Alexei Starovoitov <alexei.starovoitov@...il.com>
To: KaFai Wan <mannkafai@...il.com>
Cc: Martin KaFai Lau <martin.lau@...ux.dev>, Alexei Starovoitov <ast@...nel.org>, 
	Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, Eduard <eddyz87@...il.com>, 
	Song Liu <song@...nel.org>, Yonghong Song <yonghong.song@...ux.dev>, 
	John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
	Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>, 
	"David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
	Mykola Lysenko <mykolal@...com>, Shuah Khan <shuah@...nel.org>, 
	Kumar Kartikeya Dwivedi <memxor@...il.com>, bpf <bpf@...r.kernel.org>, 
	LKML <linux-kernel@...r.kernel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>, kafai.wan@...mail.com, 
	Leon Hwang <leon.hwang@...ux.dev>
Subject: Re: [PATCH bpf-next v3 1/2] bpf: Allow access to const void pointer
 arguments in tracing programs

On Thu, Apr 17, 2025 at 8:16 AM KaFai Wan <mannkafai@...il.com> wrote:
>
> Adding support to access arguments with const void pointer arguments
> in tracing programs.
>
> Currently we allow tracing programs to access void pointers. If we try to
> access argument which is pointer to const void like 2nd argument in kfree,
> verifier will fail to load the program with;
>
> 0: R1=ctx() R10=fp0
> ; asm volatile ("r2 = *(u64 *)(r1 + 8); ");
> 0: (79) r2 = *(u64 *)(r1 +8)
> func 'kfree' arg1 type UNKNOWN is not a struct
>
> Changing the is_int_ptr to void and generic integer check and renaming
> it to is_void_or_int_ptr.
>
> Cc: Leon Hwang <leon.hwang@...ux.dev>
> Signed-off-by: KaFai Wan <kafai.wan@...mail.com>

The patch looks good, but your SOB is different from From.
Please use the same in SOB.
And keep Acks when you respin.

pw-bot: cr