linux-kernel - Re: [PATCH 1/5] kallsyms: pass buffer size in sprint

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Message-ID: <f3627eae-f5ae-1d30-2c09-1820a255334a@redhat.com>
Date:   Fri, 20 May 2022 15:52:01 -0400
From:   Waiman Long <longman@...hat.com>
To:     Maninder Singh <maninder1.s@...sung.com>, keescook@...omium.org,
        pmladek@...e.com, bcain@...cinc.com, mpe@...erman.id.au,
        benh@...nel.crashing.org, paulus@...ba.org, hca@...ux.ibm.com,
        gor@...ux.ibm.com, agordeev@...ux.ibm.com,
        borntraeger@...ux.ibm.com, svens@...ux.ibm.com, satishkh@...co.com,
        sebaddel@...co.com, kartilak@...co.com, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, mcgrof@...nel.org,
        jason.wessel@...driver.com, daniel.thompson@...aro.org,
        dianders@...omium.org, naveen.n.rao@...ux.ibm.com,
        anil.s.keshavamurthy@...el.com, davem@...emloft.net,
        mhiramat@...nel.org, peterz@...radead.org, mingo@...hat.com,
        will@...nel.org, boqun.feng@...il.com, rostedt@...dmis.org,
        senozhatsky@...omium.org, andriy.shevchenko@...ux.intel.com,
        linux@...musvillemoes.dk, akpm@...ux-foundation.org, arnd@...db.de
Cc:     linux-hexagon@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-modules@...r.kernel.org,
        kgdb-bugreport@...ts.sourceforge.net, v.narang@...sung.com,
        onkarnath.1@...sung.com
Subject: Re: [PATCH 1/5] kallsyms: pass buffer size in sprint_* APIs

On 5/20/22 04:36, Maninder Singh wrote:
> As of now sprint_* APIs don't pass buffer size as an argument
> and use sprintf directly.
>
> To replace dangerous sprintf API to scnprintf,
> buffer size is required in arguments.
>
> Co-developed-by: Onkarnath <onkarnath.1@...sung.com>
> Signed-off-by: Onkarnath <onkarnath.1@...sung.com>
> Signed-off-by: Maninder Singh <maninder1.s@...sung.com>
> ---
>   arch/s390/lib/test_unwind.c    |  2 +-
>   drivers/scsi/fnic/fnic_trace.c |  8 ++++----
>   include/linux/kallsyms.h       | 20 ++++++++++----------
>   init/main.c                    |  2 +-
>   kernel/kallsyms.c              | 27 ++++++++++++++++-----------
>   kernel/trace/trace_output.c    |  2 +-
>   lib/vsprintf.c                 | 10 +++++-----
>   7 files changed, 38 insertions(+), 33 deletions(-)
>
> diff --git a/arch/s390/lib/test_unwind.c b/arch/s390/lib/test_unwind.c
> index 5a053b393d5c..adbc2b53db16 100644
> --- a/arch/s390/lib/test_unwind.c
> +++ b/arch/s390/lib/test_unwind.c
> @@ -75,7 +75,7 @@ static noinline int test_unwind(struct task_struct *task, struct pt_regs *regs,
>   			ret = -EINVAL;
>   			break;
>   		}
> -		sprint_symbol(sym, addr);
> +		sprint_symbol(sym, KSYM_SYMBOL_LEN, addr);

Instead of hardcoding KSYM_SYMBOL_LEN everywhere, will it better to hide 
it like this:

         extern int __sprint_symbol(char *buffer, size_t size, unsigned 
long address);
         #define sprint_symbol(buf, addr)        __sprint_symbol(buf, 
sizeof(buf), addr)

Or you can use sizeof(buf) directly instead of KSYM_SYMBOL_LEN.

Cheers,
Longman