linux-kernel - [PATCH v2 2/7] kallsyms: Clean up modname and modbuildid initialization in kallsyms_lookup

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Message-ID: <20251112142003.182062-3-pmladek@suse.com>
Date: Wed, 12 Nov 2025 15:19:58 +0100
From: Petr Mladek <pmladek@...e.com>
To: Petr Pavlu <petr.pavlu@...e.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <kees@...nel.org>
Cc: Aaron Tomlin <atomlin@...mlin.com>,
	Daniel Borkmann <daniel@...earbox.net>,
	John Fastabend <john.fastabend@...il.com>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Luis Chamberlain <mcgrof@...nel.org>,
	Daniel Gomez <da.gomez@...nel.org>,
	Sami Tolvanen <samitolvanen@...gle.com>,
	linux-kernel@...r.kernel.org,
	bpf@...r.kernel.org,
	linux-modules@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	Petr Mladek <pmladek@...e.com>
Subject: [PATCH v2 2/7] kallsyms: Clean up modname and modbuildid initialization in kallsyms_lookup_buildid()

The @modname and @modbuildid optional return parameters are set only
when the symbol is in a module.

Always initialize them so that they do not need to be cleared when
the module is not in a module. It simplifies the logic and makes
the code even slightly more safe.

Note that bpf_address_lookup() function will get updated in a separate
patch.

Signed-off-by: Petr Mladek <pmladek@...e.com>
---
 kernel/kallsyms.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index e08c1e57fc0d..ffb64eaa0505 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -359,6 +359,14 @@ static int kallsyms_lookup_buildid(unsigned long addr,
 	 * or empty string.
 	 */
 	namebuf[0] = 0;
+	/*
+	 * Initialize the module-related return values. They are not set
+	 * when the symbol is in vmlinux or it is a bpf address.
+	 */
+	if (modname)
+		*modname = NULL;
+	if (modbuildid)
+		*modbuildid = NULL;
 
 	if (is_ksym_addr(addr)) {
 		unsigned long pos;
@@ -367,10 +375,6 @@ static int kallsyms_lookup_buildid(unsigned long addr,
 		/* Grab name */
 		kallsyms_expand_symbol(get_symbol_offset(pos),
 				       namebuf, KSYM_NAME_LEN);
-		if (modname)
-			*modname = NULL;
-		if (modbuildid)
-			*modbuildid = NULL;
 
 		return strlen(namebuf);
 	}
-- 
2.51.1