From 85c44913969bd27f15229c39383da1291800d7e9 Mon Sep 17 00:00:00 2001
From: Sohom Datta <sohomdatta1@gmail.com>
Date: Sun, 4 Dec 2022 16:28:35 +0530
Subject: perf expr: Prevent normalize() from reading into undefined memory in
 the expression lexer

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@gmail.com>
Acked-by: Ian Rogers <irogers@google.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221204105836.1012885-1-sohomdatta1+git@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/expr.l | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'tools')

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;
-- 
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