linux-kernel - [PATCH 3/6] module: move freeinit allocation to avoid memory leak

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Message-ID: <20250918201109.24620-8-julian.lagattuta@gmail.com>
Date: Thu, 18 Sep 2025 16:11:10 -0400
From: julian-lagattuta <julian.lagattuta@...il.com>
To: Luis Chamberlain <mcgrof@...nel.org>,
	Petr Pavlu <petr.pavlu@...e.com>
Cc: Sami Tolvanen <samitolvanen@...gle.com>,
	Daniel Gomez <da.gomez@...sung.com>,
	linux-modules@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	julian-lagattuta <julian.lagattuta@...il.com>
Subject: [PATCH 3/6] module: move freeinit allocation to avoid memory leak

move freeinit allocation after do_one_initcall in case do_one_initcall crashes.
Otherwise, freeinit would leak memory after every initalization of a crashed module.
I could not find a reason for why freeinit allocation happened before do_one_initcall.

Signed-off-by: julian-lagattuta <julian.lagattuta@...il.com>
---
 kernel/module/main.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/kernel/module/main.c b/kernel/module/main.c
index 2277c53aef2e..2825ac177c62 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -3021,21 +3021,13 @@ static noinline int do_init_module(struct module *mod)
 	}
 #endif
 
-	freeinit = kmalloc(sizeof(*freeinit), GFP_KERNEL);
-	if (!freeinit) {
-		ret = -ENOMEM;
-		goto fail;
-	}
-	freeinit->init_text = mod->mem[MOD_INIT_TEXT].base;
-	freeinit->init_data = mod->mem[MOD_INIT_DATA].base;
-	freeinit->init_rodata = mod->mem[MOD_INIT_RODATA].base;
 
 	do_mod_ctors(mod);
 	/* Start the module */
 	if (mod->init != NULL)
 		ret = do_one_initcall(mod->init);
 	if (ret < 0) {
-		goto fail_free_freeinit;
+		goto fail;
 	}
 	if (ret > 0) {
 		pr_warn("%s: '%s'->init suspiciously returned %d, it should "
@@ -3045,6 +3037,14 @@ static noinline int do_init_module(struct module *mod)
 		dump_stack();
 	}
 
+	freeinit = kmalloc(sizeof(*freeinit), GFP_KERNEL);
+	if (!freeinit) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+	freeinit->init_text = mod->mem[MOD_INIT_TEXT].base;
+	freeinit->init_data = mod->mem[MOD_INIT_DATA].base;
+	freeinit->init_rodata = mod->mem[MOD_INIT_RODATA].base;
 	/* Now it's a first class citizen! */
 	mod->state = MODULE_STATE_LIVE;
 	blocking_notifier_call_chain(&module_notify_list,
@@ -3123,8 +3123,6 @@ static noinline int do_init_module(struct module *mod)
 
 	return 0;
 
-fail_free_freeinit:
-	kfree(freeinit);
 fail:
 	/* Try to protect us from buggy refcounters. */
 	mod->state = MODULE_STATE_GOING;
-- 
2.45.2