linux-kernel - Re: [PATCH 1/4] arm64: ptdump: use seq_puts() in pt_dump_seq

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <aQNyaoXKsMdkIDrc@willie-the-truck>
Date: Thu, 30 Oct 2025 14:12:58 +0000
From: Will Deacon <will@...nel.org>
To: Josephine Pfeiffer <hi@...ie.lol>
Cc: catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] arm64: ptdump: use seq_puts() in pt_dump_seq_puts()
 macro

On Sat, Oct 18, 2025 at 07:04:16PM +0200, Josephine Pfeiffer wrote:
> The pt_dump_seq_puts() macro incorrectly uses seq_printf() instead of
> seq_puts(). This is both a performance issue and conceptually wrong,
> as the macro name suggests plain string output (puts) but the
> implementation uses formatted output (printf).
> 
> All call sites pass constant strings without format specifiers, so
> using seq_printf() adds unnecessary overhead for format string parsing.
> 
> This bug was introduced in commit ae5d1cf358a5 ("arm64: dump: Make the
> page table dumping seq_file optional") in 2016, where seq_puts() was
> replaced with a new pt_dump_seq_puts() macro that mistakenly used
> seq_printf().
> 
> Fixes: ae5d1cf358a5 ("arm64: dump: Make the page table dumping seq_file optional")
> Signed-off-by: Josephine Pfeiffer <hi@...ie.lol>
> ---
>  arch/arm64/mm/ptdump.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c
> index ab9899ca1e5f..a35fcd62bf75 100644
> --- a/arch/arm64/mm/ptdump.c
> +++ b/arch/arm64/mm/ptdump.c
> @@ -35,7 +35,7 @@
>  #define pt_dump_seq_puts(m, fmt)	\
>  ({					\
>  	if (m)				\
> -		seq_printf(m, fmt);	\
> +		seq_puts(m, fmt);	\
>  })

This looks fine to me but I'm slightly confused as this patch is marked
as 1/4 but I can't find the other three anywhere. Is that just an error
or is this part of a bigger series?

Thanks,

Will