linux-kernel - Re: [PATCH 1/2] tracing: Check total refcount before releasing bufs in profile

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]

Message-ID: <19148.1579.573095.98045@cargo.ozlabs.ibm.com>
Date:	Wed, 7 Oct 2009 14:08:27 +1100
From:	Paul Mackerras <paulus@...ba.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Li Zefan <lizf@...fujitsu.com>
Subject: Re: [PATCH 1/2] tracing: Check total refcount before releasing bufs in profile_enable failure

Frederic Weisbecker writes:

> When we call the profile_enable() callback of an event, we release the
> shared perf event tracing buffers unconditionnaly in the failure path.
> This is wrong because there may be other users of these. Then check the
> total refcount before doing this.

[snip]

> -	kfree(trace_profile_buf_nmi);
>  fail_buf_nmi:
> -	kfree(trace_profile_buf);
> +	if (!total_profile_count) {

A small problem here: total_profile_count will be 1, not 0, in the
case where we need to free...

> +		kfree(trace_profile_buf_nmi);
> +		kfree(trace_profile_buf);
> +		trace_profile_buf_nmi = NULL;
> +		trace_profile_buf = NULL;
> +	}
>  fail_buf:
> -	total_profile_count--;

since we don't decrement total_profile_count until here.

Paul.
--
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/