linux-kernel - Re: [PATCH] Prevent normalize() from reading into undefined memory

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Date:   Sun, 8 Jan 2023 15:12:55 +0100
From:   Jiri Olsa <olsajiri@...il.com>
To:     Sohom Datta <sohomdatta1@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Sohom Datta <sohomdatta1+git@...il.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Prevent normalize() from reading into undefined memory

On Sun, Dec 04, 2022 at 04:28:35PM +0530, Sohom Datta wrote:
> The current implementation does not account for a
> trailing backslash followed by a null-byte. If a
> null-byte is encountered following a backslash,
> normalize() will continue reading (and potentially
> writing) into garbage memory ignoring the EOS
> null-byte.
> 
> Signed-off-by: Sohom Datta <sohomdatta1+git@...il.com>

Acked-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka

> ---
>  tools/perf/util/expr.l | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/expr.l b/tools/perf/util/expr.l
> index 0168a9637330..d47de5f270a8 100644
> --- a/tools/perf/util/expr.l
> +++ b/tools/perf/util/expr.l
> @@ -42,8 +42,11 @@ static char *normalize(char *str, int runtime)
>  	char *dst = str;
>  
>  	while (*str) {
> -		if (*str == '\\')
> +		if (*str == '\\') {
>  			*dst++ = *++str;
> +			if (!*str)
> +				break;
> +		}
>  		else if (*str == '?') {
>  			char *paramval;
>  			int i = 0;
> -- 
> 2.38.1
>