linux-kernel - [PATCH AUTOSEL 4.14 02/66] tomoyo: fix clang pointer arithmetic warning

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Message-Id: <20201223022253.2793452-2-sashal@kernel.org>
Date:   Tue, 22 Dec 2020 21:21:48 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Arnd Bergmann <arnd@...db.de>,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        Sasha Levin <sashal@...nel.org>,
        linux-security-module@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: [PATCH AUTOSEL 4.14 02/66] tomoyo: fix clang pointer arithmetic warning

From: Arnd Bergmann <arnd@...db.de>

[ Upstream commit d9594e0409651a237903a13c9718df889f43d43b ]

clang warns about additions on NULL pointers being undefined in C:

security/tomoyo/securityfs_if.c:226:59: warning: arithmetic on a null pointer treated as a cast from integer to pointer is a GNU extension [-Wnull-pointer-arithmetic]
        securityfs_create_file(name, mode, parent, ((u8 *) NULL) + key,

Change the code to instead use a cast through uintptr_t to avoid
the warning.

Signed-off-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 security/tomoyo/securityfs_if.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/security/tomoyo/securityfs_if.c b/security/tomoyo/securityfs_if.c
index 49393c2a3f8bc..9c7c8ec87de2a 100644
--- a/security/tomoyo/securityfs_if.c
+++ b/security/tomoyo/securityfs_if.c
@@ -131,8 +131,8 @@ static const struct file_operations tomoyo_self_operations = {
  */
 static int tomoyo_open(struct inode *inode, struct file *file)
 {
-	const int key = ((u8 *) file_inode(file)->i_private)
-		- ((u8 *) NULL);
+	const u8 key = (uintptr_t) file_inode(file)->i_private;
+
 	return tomoyo_open_control(key, file);
 }
 
@@ -223,7 +223,7 @@ static const struct file_operations tomoyo_operations = {
 static void __init tomoyo_create_entry(const char *name, const umode_t mode,
 				       struct dentry *parent, const u8 key)
 {
-	securityfs_create_file(name, mode, parent, ((u8 *) NULL) + key,
+	securityfs_create_file(name, mode, parent, (void *) (uintptr_t) key,
 			       &tomoyo_operations);
 }
 
-- 
2.27.0