linux-kernel - Re: [PATCH 1/1] ftrace: do not update max buffer with no users

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

Date:	Wed, 12 Nov 2008 18:37:45 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>,
	Pekka Paalanen <pq@....fi>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Steven Rostedt <srostedt@...hat.com>
Subject: Re: [PATCH 1/1] ftrace: do not update max buffer with no users

On Wed, 12 Nov 2008 20:30:42 -0500 Steven Rostedt <rostedt@...dmis.org> wrote:

> Impact: only use max latency buffer when a user is configured
> 
> Pekka reported a bug with the resizing of the buffers when only the
> MMIO tracer was configured. The issue was, to save memory, the max
> latency trace buffer was only initialized if a tracer that uses it
> is configured in.
> 
> What happened was that the max latency buffer was never initialized
> when only the MMIO tracer was configurued. The MMIO tracer does not
> use the max tracer, which kept it from being initialized. But the
> resize code still tried to resize the max latency buffers, but because
> they were never allocated, the resize code was passed a NULL pointer.
> 
> This patch puts all of the max_tr (max tracer buffer) inside the
> TRACER_MAX_TRACE config, to prevent any more errors in its use when
> not configured.
> 
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif /* CONFIG_TRACER_MAX_TRACE */
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif
> +#ifdef CONFIG_TRACER_MAX_TRACE
> +#endif

hey.


This sort of thing:

+#ifdef CONFIG_TRACER_MAX_TRACE
 	if (current_trace && current_trace->print_max)
 		iter->tr = &max_tr;
 	else
+#endif
 		iter->tr = inode->i_private;

is particularly regrettable.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/