Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
Date:   Fri, 26 Jul 2019 16:05:41 -0300
To:     Vince Weaver <vincent.weaver@maine.edu>
Cc:     linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@redhat.com>,
        Namhyung Kim <namhyung@kernel.org>
Subject: Re: [patch] perf tool buffer overflow in perf_header__read_build_ids
Message-ID: <20190726190541.GC20482@kernel.org>
References: <alpine.DEB.2.21.1907231100440.14532@macbook-air>
 <alpine.DEB.2.21.1907231639120.14532@macbook-air>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.2.21.1907231639120.14532@macbook-air>
User-Agent: Mutt/1.12.0 (2019-05-25)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Em Tue, Jul 23, 2019 at 04:42:30PM -0400, Vince Weaver escreveu:
> Hello
> 
> my perf_tool_fuzzer has found another issue, this one a buffer overflow
> in perf_header__read_build_ids.  The build id filename is read in with a 
> filename length read from the perf.data file, but this can be longer than
> PATH_MAX which will smash the stack.
> 
> This might not be the right fix, not sure if filename should be NUL
> terminated or not.
> 
> Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
> 
> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
> index c24db7f4909c..9a893a26e678 100644
> --- a/tools/perf/util/header.c
> +++ b/tools/perf/util/header.c
> @@ -2001,6 +2001,9 @@ static int perf_header__read_build_ids(struct perf_header *header,
>  			perf_event_header__bswap(&bev.header);
>  
>  		len = bev.header.size - sizeof(bev);
> +
> +		if (len>PATH_MAX) len=PATH_MAX;
> +

Humm, I wonder if we shouldn't just declare the whole file invalid like
you did with the previous patch?

- Arnaldo

>  		if (readn(input, filename, len) != len)
>  			goto out;
>  		/*