linux-kernel - [PATCH 1/1] perf tool: fix handling NULL al->maps returned from thread__find

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Message-ID: <20240708232302.15267-2-cachen@purestorage.com>
Date: Mon,  8 Jul 2024 17:23:01 -0600
From: Casey Chen <cachen@...estorage.com>
To: linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: yzhong@...estorage.com,
	Casey Chen <cachen@...estorage.com>
Subject: [PATCH 1/1] perf tool: fix handling NULL al->maps returned from thread__find_map

With 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions"),
thread__find_map() would return with al->maps or al->map being NULL
when cpumode is 3 (macro PERF_RECORD_MISC_HYPERVISOR),
later deferencing on it would crash.

Fix callers of thread__find_map() or thread__find_symbol() to handle
this.
---
 tools/perf/arch/powerpc/util/skip-callchain-idx.c | 10 ++++++----
 tools/perf/util/machine.c                         |  5 +++++
 tools/perf/util/unwind-libdw.c                    |  6 ++++--
 3 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/tools/perf/arch/powerpc/util/skip-callchain-idx.c b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
index 5f3edb3004d8..25b0804df4c4 100644
--- a/tools/perf/arch/powerpc/util/skip-callchain-idx.c
+++ b/tools/perf/arch/powerpc/util/skip-callchain-idx.c
@@ -255,13 +255,14 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
 
 	thread__find_symbol(thread, PERF_RECORD_MISC_USER, ip, &al);
 
-	if (al.map)
-		dso = map__dso(al.map);
+	if (!al.map)
+		goto out;
+
+	dso = map__dso(al.map);
 
 	if (!dso) {
 		pr_debug("%" PRIx64 " dso is NULL\n", ip);
-		addr_location__exit(&al);
-		return skip_slot;
+		goto out;
 	}
 
 	rc = check_return_addr(dso, map__start(al.map), ip);
@@ -282,6 +283,7 @@ int arch_skip_callchain_idx(struct thread *thread, struct ip_callchain *chain)
 		skip_slot = 3;
 	}
 
+out:
 	addr_location__exit(&al);
 	return skip_slot;
 }
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 8477edefc299..fa4037d7f3d4 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -2098,7 +2098,12 @@ static int add_callchain_ip(struct thread *thread,
 			}
 			goto out;
 		}
+
 		thread__find_symbol(thread, *cpumode, ip, &al);
+		if (!al.maps || !al.map) {
+			err = 1;
+			goto out;
+		}
 	}
 
 	if (al.sym != NULL) {
diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index b38d322734b4..fb038ef55be2 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -53,8 +53,10 @@ static int __report_module(struct addr_location *al, u64 ip,
 	 */
 	thread__find_symbol(ui->thread, PERF_RECORD_MISC_USER, ip, al);
 
-	if (al->map)
-		dso = map__dso(al->map);
+	if (!al->map)
+		return -1;
+
+	dso = map__dso(al->map);
 
 	if (!dso)
 		return 0;
-- 
2.45.2