[PATCH 03/11] perf tools: Use perf_env__get_cpu_topology() in machine__resolve()

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Arnaldo Carvalho de Melo <acme@redhat.com>

machine__resolve() accesses env->cpu[al->cpu].socket_id after checking
al->cpu >= 0 and env->cpu != NULL, but without validating al->cpu
against env->nr_cpus_avail.  Since al->cpu comes from the untrusted
perf.data sample, a crafted file with a large CPU index causes an
out-of-bounds heap read.

Use perf_env__get_cpu_topology() which validates both NULL and bounds.
Also bounds-check al->cpu before the cast to struct perf_cpu (int16_t):
without this, values like 65536 silently truncate to 0, bypassing the
accessor's internal check and returning CPU 0's topology.

Fixes: 0c4c4debb0adda4c ("perf tools: Add processor socket info to hist_entry and addr_location")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Ian Rogers <irogers@google.com>
Assisted-by: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/event.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index 66f4843bb235df53..ea75816d126a14be 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -14,6 +14,7 @@
 #include <linux/perf_event.h>
 #include "cpumap.h"
 #include "dso.h"
+#include "env.h"
 #include "event.h"
 #include "debug.h"
 #include "hist.h"
@@ -836,8 +837,18 @@ int machine__resolve(struct machine *machine, struct addr_location *al,
 	if (al->cpu >= 0) {
 		struct perf_env *env = machine->env;
 
-		if (env && env->cpu)
-			al->socket = env->cpu[al->cpu].socket_id;
+		/*
+		 * Bounds-check al->cpu (s32) before casting to struct perf_cpu
+		 * (int16_t): without this, e.g. 65536 truncates to 0 and silently
+		 * returns CPU 0's topology.  Can go once perf_cpu.cpu is widened.
+		 */
+		if (env && al->cpu < env->nr_cpus_avail) {
+			struct cpu_topology_map *topo;
+
+			topo = perf_env__get_cpu_topology(env, (struct perf_cpu){ al->cpu });
+			if (topo)
+				al->socket = topo->socket_id;
+		}
 	}
 
 	/* Account for possible out-of-order switch events. */
-- 
2.54.0