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Message-ID: <20240722191858.123607-1-cachen@purestorage.com>
Date: Mon, 22 Jul 2024 13:18:58 -0600
From: Casey Chen <cachen@...estorage.com>
To: linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
namhyung@...nel.org,
irogers@...gle.com
Cc: yzhong@...estorage.com,
Casey Chen <cachen@...estorage.com>
Subject: [PATCHv4] perf tool: fix dereferencing NULL al->maps
With 0dd5041c9a0e ("perf addr_location: Add init/exit/copy functions"),
when cpumode is 3 (macro PERF_RECORD_MISC_HYPERVISOR),
thread__find_map() could return with al->maps being NULL.
The path below could add a callchain_cursor_node with NULL ms.maps.
add_callchain_ip()
thread__find_symbol(.., &al)
thread__find_map(.., &al) // al->maps becomes NULL
ms.maps = maps__get(al.maps)
callchain_cursor_append(..., &ms, ...)
node->ms.maps = maps__get(ms->maps)
Then the path below would dereference NULL maps and get segfault.
fill_callchain_info()
maps__machine(node->ms.maps);
Fix it by checking if maps is NULL in fill_callchain_info().
---
tools/perf/util/callchain.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
index 1730b852a947..6d075648d2cc 100644
--- a/tools/perf/util/callchain.c
+++ b/tools/perf/util/callchain.c
@@ -1141,7 +1141,7 @@ int hist_entry__append_callchain(struct hist_entry *he, struct perf_sample *samp
int fill_callchain_info(struct addr_location *al, struct callchain_cursor_node *node,
bool hide_unresolved)
{
- struct machine *machine = maps__machine(node->ms.maps);
+ struct machine *machine = node->ms.maps ? maps__machine(node->ms.maps) : NULL;
maps__put(al->maps);
al->maps = maps__get(node->ms.maps);
--
2.45.2
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