From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, linux-security-module@vger.kernel.org
Subject: Re: [PATCH] tomoyo: fix clang pointer arithmetic warning
Date: Wed, 28 Oct 2020 22:22:59 +0900 [thread overview]
Message-ID: <7bb56fd2-ffe2-2985-19d0-31b42bc9e7e8@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20201026215236.3894200-1-arnd@kernel.org>
Thank you for a patch. I have two questions.
On 2020/10/27 6:52, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> 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.
>
> - securityfs_create_file(name, mode, parent, ((u8 *) NULL) + key,
> + securityfs_create_file(name, mode, parent, (u8 *)(uintptr_t)key,
> &tomoyo_operations);
(1) Does clang warn if "(void *)key" is used instead of "(u8 *)(uintptr_t)key" ?
(2) tomoyo_open() has
const int key = ((u8 *) file_inode(file)->i_private) - ((u8 *) NULL);
which decodes the "u8 key" passed to tomoyo_create_entry(). For symmetry,
I'd like to remove NULL from tomoyo_open() as well. Does clang warn if
const int key = (u8) (file_inode(file)->i_private);
is used?
next prev parent reply other threads:[~2020-10-28 23:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 21:52 [PATCH] tomoyo: fix clang pointer arithmetic warning Arnd Bergmann
2020-10-28 13:22 ` Tetsuo Handa [this message]
2020-10-28 13:57 ` Arnd Bergmann
2020-10-28 14:18 ` Tetsuo Handa
2020-11-11 20:00 ` Nick Desaulniers
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