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Date: Wed, 29 Aug 2012 00:29:33 -0600
From: David Ahern <dsahern@gmail.com>
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To: "Suzuki K. Poulose" <suzuki@in.ibm.com>
CC: Arnaldo Carvalho de Melo <acme@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Frederic Weisbecker <fweisbec@gmail.com>, ananth@in.ibm.com,
        Ingo Molnar <mingo@kernel.org>, Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH] [perf] Remove the node from rblist in strlist__remove
References: <20120829055840.7802.1459.stgit@suzukikp.in.ibm.com>
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On 8/29/12 12:00 AM, Suzuki K. Poulose wrote:
> The following commit:
>
> author	David Ahern <dsahern@gmail.com>
> 	Tue, 31 Jul 2012 04:31:33 +0000 (22:31 -0600)
> committer	Arnaldo Carvalho de Melo <acme@redhat.com>
> 	Fri, 3 Aug 2012 13:39:51 +0000 (10:39 -0300)
> commit	ee8dd3ca43f151d9fbe1edeef68fb8a77eb9f047
>
> causes a double free during a probe deletion as the node is
> never removed from the list via strlist__remove(), even though
> it gets 'deleted' (read free()'d). This causes a double
> free when we do strlist__delete() as the node is already deleted
> but present in the rblist.
>
> [suzukikp@suzukikp perf]$ sudo ./perf probe -a do_fork
> Added new event:
>    probe:do_fork        (on do_fork)
>
> You can now use it in all perf tools, such as:
>
> 	perf record -e probe:do_fork -aR sleep 1
>
> [suzukikp@suzukikp perf]$ sudo ./perf probe -d do_fork
> Removed event: probe:do_fork
> *** glibc detected *** ./perf: double free or corruption (fasttop): 0x000000000133d600 ***
> ======= Backtrace: =========
> /lib64/libc.so.6[0x38eec7dda6]
> ./perf(rblist__delete+0x5c)[0x47d3dc]
> ./perf(del_perf_probe_events+0xb6)[0x47b826]
> ./perf(cmd_probe+0x471)[0x42c8d1]
> ./perf[0x4150b3]
> ./perf(main+0x501)[0x4148e1]
> /lib64/libc.so.6(__libc_start_main+0xed)[0x38eec2169d]
> ./perf[0x414a61]
>
>
> Make sure we remove the node from the rblist before we delete the
> node. The rblist__remove_node() will invoke rblist->node_delete,
> which  will take care of deleting the node with the suitable function
> provided by the user.
>
> Reported-by: Ananth N. Mavinakayanahalli <ananth@in.ibm.com>
> Signed-off-by: Suzuki K. Poulose <suzuki@in.ibm.com>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Arnaldo Carvalho de Melo <acme@infradead.org>

Acked-by: David Ahern <dsahern@gmail.com>

Same type of change is needed for util/intlist.c if you want to submit 
one, otherwise I will take care of it.

David