linux-kernel - [PATCH v3 08/23] dynamic_debug: don't duplicate modname in ddebug_add

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20181109231021.11658-9-linux@rasmusvillemoes.dk>
Date:   Sat, 10 Nov 2018 00:10:06 +0100
From:   Rasmus Villemoes <linux@...musvillemoes.dk>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Jason Baron <jbaron@...mai.com>
Cc:     linux-kernel@...r.kernel.org,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH v3 08/23] dynamic_debug: don't duplicate modname in ddebug_add_module

For built-in modules, we're already reusing the passed-in string via
kstrdup_const(). But for actual modules (i.e. when we're called from
dynamic_debug_setup in module.c), the passed-in string (which points
at the name[] array inside struct module) is also
guaranteed to live at least as long as the struct ddebug_table, since
free_module() calls ddebug_remove_module().

Acked-by: Jason Baron <jbaron@...mai.com>
Signed-off-by: Rasmus Villemoes <linux@...musvillemoes.dk>
---
 lib/dynamic_debug.c | 15 +++++++--------
 1 file changed, 7 insertions(+), 8 deletions(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index c7c96bc7654a..2155e0e23530 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -847,17 +847,17 @@ int ddebug_add_module(struct _ddebug *tab, unsigned int n,
 			     const char *name)
 {
 	struct ddebug_table *dt;
-	const char *new_name;
 
 	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
 	if (dt == NULL)
 		return -ENOMEM;
-	new_name = kstrdup_const(name, GFP_KERNEL);
-	if (new_name == NULL) {
-		kfree(dt);
-		return -ENOMEM;
-	}
-	dt->mod_name = new_name;
+	/*
+	 * For built-in modules, name lives in .rodata and is
+	 * immortal. For loaded modules, name points at the name[]
+	 * member of struct module, which lives at least as long as
+	 * this struct ddebug_table.
+	 */
+	dt->mod_name = name;
 	dt->num_ddebugs = n;
 	dt->ddebugs = tab;
 
@@ -913,7 +913,6 @@ int ddebug_dyndbg_module_param_cb(char *param, char *val, const char *module)
 static void ddebug_table_free(struct ddebug_table *dt)
 {
 	list_del_init(&dt->link);
-	kfree_const(dt->mod_name);
 	kfree(dt);
 }
 
-- 
2.19.1.6.gbde171bbf5