linux-kernel - [PATCH] livepatch: Reorder to use before freeing a pointer

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20220319165159.2170650-1-trix@redhat.com>
Date:   Sat, 19 Mar 2022 09:51:59 -0700
From:   trix@...hat.com
To:     jpoimboe@...hat.com, jikos@...nel.org, mbenes@...e.cz,
        pmladek@...e.com, joe.lawrence@...hat.com, nathan@...nel.org,
        ndesaulniers@...gle.com
Cc:     live-patching@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Tom Rix <trix@...hat.com>
Subject: [PATCH] livepatch: Reorder to use before freeing a pointer

From: Tom Rix <trix@...hat.com>

Clang static analysis reports this issue
livepatch-shadow-fix1.c:113:2: warning: Use of
  memory after it is freed
  pr_info("%s: dummy @ %p, prevented leak @ %p\n",
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The pointer is freed in the previous statement.
Reorder the pr_info to report before the free.

Signed-off-by: Tom Rix <trix@...hat.com>
---
 samples/livepatch/livepatch-shadow-fix1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
index 918ce17b43fda..6701641bf12d4 100644
--- a/samples/livepatch/livepatch-shadow-fix1.c
+++ b/samples/livepatch/livepatch-shadow-fix1.c
@@ -109,9 +109,9 @@ static void livepatch_fix1_dummy_leak_dtor(void *obj, void *shadow_data)
 	void *d = obj;
 	int **shadow_leak = shadow_data;
 
-	kfree(*shadow_leak);
 	pr_info("%s: dummy @ %p, prevented leak @ %p\n",
 			 __func__, d, *shadow_leak);
+	kfree(*shadow_leak);
 }
 
 static void livepatch_fix1_dummy_free(struct dummy *d)
-- 
2.26.3