[PATCH v2 3/3] perf header: Fix potential memory corruption in cpu_cache_level__read

[Ian Rogers <irogers@google.com>]

strim may advance the pointer assigned to cache->size which causes
later frees to crash. Fix by performing the strim and then memmove-ing
the potentially shifted string back over the original string. The bug
was introduced by the transition from rtrim to strim, as rtrim
wouldn't move on the left.

Fixes: 13c230ab6e56 ("perf tools: Ditch rtrim(), use strim() from tools/lib")
Signed-off-by: Ian Rogers <irogers@google.com>
Assisted-by: Antigravity:gemini-3.1-pro
---
 tools/perf/util/header.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index bdd79d7542ef..78b16a098148 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -1267,7 +1267,11 @@ static int cpu_cache_level__read(struct cpu_cache_level *cache, u32 cpu, u16 lev
 		return -1;
 
 	cache->type[len] = 0;
-	cache->type = strim(cache->type);
+	{
+		char *trimmed = strim(cache->type);
+
+		memmove(cache->type, trimmed, strlen(trimmed) + 1);
+	}
 
 	scnprintf(file, PATH_MAX, "%s/size", path);
 	if (sysfs__read_str(file, &cache->size, &len)) {
@@ -1276,7 +1280,11 @@ static int cpu_cache_level__read(struct cpu_cache_level *cache, u32 cpu, u16 lev
 	}
 
 	cache->size[len] = 0;
-	cache->size = strim(cache->size);
+	{
+		char *trimmed = strim(cache->size);
+
+		memmove(cache->size, trimmed, strlen(trimmed) + 1);
+	}
 
 	scnprintf(file, PATH_MAX, "%s/shared_cpu_list", path);
 	if (sysfs__read_str(file, &cache->map, &len)) {
@@ -1286,7 +1294,11 @@ static int cpu_cache_level__read(struct cpu_cache_level *cache, u32 cpu, u16 lev
 	}
 
 	cache->map[len] = 0;
-	cache->map = strim(cache->map);
+	{
+		char *trimmed = strim(cache->map);
+
+		memmove(cache->map, trimmed, strlen(trimmed) + 1);
+	}
 	return 0;
 }
 
-- 
2.55.0.1007.g17ff1f9808-goog