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From: Petr Mladek <pmladek@suse.com>
To: Petr Pavlu <petr.pavlu@suse.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <kees@kernel.org>
Cc: Aaron Tomlin <atomlin@atomlin.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	John Fastabend <john.fastabend@gmail.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Daniel Gomez <da.gomez@kernel.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
	linux-modules@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org,
	Petr Mladek <pmladek@suse.com>
Subject: [PATCH v2 2/7] kallsyms: Clean up modname and modbuildid initialization in kallsyms_lookup_buildid()
Date: Wed, 12 Nov 2025 15:19:58 +0100	[thread overview]
Message-ID: <20251112142003.182062-3-pmladek@suse.com> (raw)
In-Reply-To: <20251112142003.182062-1-pmladek@suse.com>

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@suse.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


  parent reply	other threads:[~2025-11-12 14:20 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-11-12 14:19 [PATCH v2 0/7] kallsyms: Prevent invalid access when showing module buildid Petr Mladek
2025-11-12 14:19 ` [PATCH v2 1/7] kallsyms: Clean up @namebuf initialization in kallsyms_lookup_buildid() Petr Mladek
2025-11-12 14:19 ` Petr Mladek [this message]
2025-11-12 14:19 ` [PATCH v2 3/7] module: Add helper function for reading module_buildid() Petr Mladek
2025-11-12 14:20 ` [PATCH v2 4/7] kallsyms: Cleanup code for appending the module buildid Petr Mladek
2025-11-12 14:20 ` [PATCH v2 5/7] kallsyms/bpf: Rename __bpf_address_lookup() to bpf_address_lookup() Petr Mladek
2025-11-13  2:50   ` Alexei Starovoitov
2025-11-12 14:20 ` [PATCH v2 6/7] kallsyms/ftrace: Set module buildid in ftrace_mod_address_lookup() Petr Mladek
2025-11-12 14:20 ` [PATCH v2 7/7] kallsyms: Prevent module removal when printing module name and buildid Petr Mladek

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