linux-kernel - [RFC] perf subcmd: avoid crash in exclude

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Message-ID: <20250910081655.355971-1-hupu.gm@gmail.com>
Date: Wed, 10 Sep 2025 16:16:55 +0800
From: hupu <hupu.gm@...il.com>
To: irogers@...gle.com,
	namhyung@...nel.org,
	linux-kernel@...r.kernel.org
Cc: hupu.gm@...il.com
Subject: [RFC] perf subcmd: avoid crash in exclude_cmds when excludes is empty

When cross-compiling the perf tool for ARM64, `perf help` may crash
with the following assertion failure:

  help.c:122: exclude_cmds: Assertion `cmds->names[ci] == NULL' failed.

This happens when the perf binary is not named exactly "perf" or when
multiple "perf-*" binaries exist in the same directory. In such cases,
the `excludes` command list can be empty, which leads to the final
assertion in exclude_cmds() being triggered.

Add a simple guard at the beginning of exclude_cmds() to return early
if excludes->cnt is zero, preventing the crash.

Signed-off-by: hupu <hupu.gm@...il.com>
---
 tools/lib/subcmd/help.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/lib/subcmd/help.c b/tools/lib/subcmd/help.c
index 9ef569492560..ddaeb4eb3e24 100644
--- a/tools/lib/subcmd/help.c
+++ b/tools/lib/subcmd/help.c
@@ -75,6 +75,9 @@ void exclude_cmds(struct cmdnames *cmds, struct cmdnames *excludes)
 	size_t ci, cj, ei;
 	int cmp;

+	if (!excludes->cnt)
+		return;
+
 	ci = cj = ei = 0;
 	while (ci < cmds->cnt && ei < excludes->cnt) {
 		cmp = strcmp(cmds->names[ci]->name, excludes->names[ei]->name);
-- 
2.43.0