[PATCH][next] apparmor: Use struct_size() helper in kmalloc()

From: "Gustavo A. R. Silva" <gustavoars@kernel.org>
To: John Johansen <john.johansen@canonical.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	linux-hardening@vger.kernel.org
Subject: [PATCH][next] apparmor: Use struct_size() helper in kmalloc()
Date: Mon, 24 Jan 2022 19:56:06 -0600	[thread overview]
Message-ID: <20220125015606.GA28243@embeddedor> (raw)

Make use of the struct_size() helper instead of an open-coded version,
in order to avoid any potential type mistakes or integer overflows that,
in the worst scenario, could lead to heap overflows.

Also, address the following sparse warnings:
security/apparmor/lib.c:139:23: warning: using sizeof on a flexible structure

Link: https://github.com/KSPP/linux/issues/174
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 security/apparmor/lib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
index fa49b81eb54c..5eda003c0d45 100644
--- a/security/apparmor/lib.c
+++ b/security/apparmor/lib.c
@@ -136,7 +136,7 @@ __counted char *aa_str_alloc(int size, gfp_t gfp)
 {
 	struct counted_str *str;
 
-	str = kmalloc(sizeof(struct counted_str) + size, gfp);
+	str = kmalloc(struct_size(str, name, size), gfp);
 	if (!str)
 		return NULL;
 
-- 
2.27.0

