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From:   Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Date:   Mon, 29 May 2023 16:50:45 +0200
Message-ID: <CANiq72n_eso7_pgna8ukmEnuCQPsKYPr0NU-Ss9Nwv0VzX=etg@mail.gmail.com>
Subject: Re: [PATCH 1/1] arch:hexagon/powerpc: use KSYM_NAME_LEN in array size
To:     maninder1.s@samsung.com,
        "keescook@chromium.org" <keescook@chromium.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Masami Hiramatsu <mhiramat@kernel.org>
Cc:     "bcain@quicinc.com" <bcain@quicinc.com>,
        "mpe@ellerman.id.au" <mpe@ellerman.id.au>,
        "npiggin@gmail.com" <npiggin@gmail.com>,
        "christophe.leroy@csgroup.eu" <christophe.leroy@csgroup.eu>,
        "nathanl@linux.ibm.com" <nathanl@linux.ibm.com>,
        "ustavoars@kernel.org" <ustavoars@kernel.org>,
        "alex.gaynor@gmail.com" <alex.gaynor@gmail.com>,
        "gary@garyguo.net" <gary@garyguo.net>,
        "ojeda@kernel.org" <ojeda@kernel.org>,
        "pmladek@suse.com" <pmladek@suse.com>,
        "linux-hexagon@vger.kernel.org" <linux-hexagon@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        Onkarnath <onkarnath.1@samsung.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>
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On Mon, May 29, 2023 at 1:08=E2=80=AFPM Maninder Singh <maninder1.s@samsung=
.com> wrote:
>
> I Will add co-developed-by` tag.
> because this change was identified while we were working on kallsyms some=
 time back.
> https://lore.kernel.org/lkml/YonTOL4zC4CytVrn@infradead.org/t/
>
> this patch set is pending and we will start working on that again, so i t=
hought better
> to send bugfix first.

Sounds good to me!

(Fixed Wedson's email address)

> Yes, I think second buffer was not related to kallsyms, so I have not tou=
ched that.

Kees: what is the current stance on `[static N]` parameters? Something like=
:

    const char *kallsyms_lookup(unsigned long addr,
                                unsigned long *symbolsize,
                                unsigned long *offset,
    -                           char **modname, char *namebuf);
    +                           char **modname, char namebuf[static
KSYM_NAME_LEN]);

makes the compiler complain about cases like these (even if trivial):

    arch/powerpc/xmon/xmon.c:1711:10: error: array argument is too small;
        contains 128 elements, callee requires at least 512
[-Werror,-Warray-bounds]
            name =3D kallsyms_lookup(pc, &size, &offset, NULL, tmpstr);
                 ^                                           ~~~~~~
    ./include/linux/kallsyms.h:86:29: note: callee declares array
parameter as static here
            char **modname, char namebuf[static KSYM_NAME_LEN]);
                                 ^      ~~~~~~~~~~~~~~~~~~~~~~

But I only see 2 files in the kernel using `[static N]` (from 2020 and
2021). Should something else be used instead (e.g. `__counted_by`),
even if constexpr-sized?.

Also, I went through the other callers to `kallsyms_lookup` to see
other issues -- one I am not sure about is `fetch_store_symstring` in
`kernel/trace/trace_probe_tmpl.h`. Steven/Masami: is that "with max
length" in the function docs enough? Is it 0xffff?

Thanks!

Cheers,
Miguel