linux-kernel - Re: [PATCH] security: tomoyo: fix error return code of tomoyo_update

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Message-ID: <79dd201e-ea6e-8de5-6250-25c23453448d@i-love.sakura.ne.jp>
Date:   Sat, 6 Mar 2021 22:37:49 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
To:     Jia-Ju Bai <baijiaju1990@...il.com>
Cc:     linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, jmorris@...ei.org, serge@...lyn.com
Subject: Re: [PATCH] security: tomoyo: fix error return code of
 tomoyo_update_domain()

On 2021/03/06 22:03, Jia-Ju Bai wrote:
> When mutex_lock_interruptible() fails, the error return code of
> tomoyo_update_domain() is not properly assigned.
> To fix this bug, error is assigned with the return value of
> mutex_lock_interruptible(), and then error is checked.

Thanks for a patch, but this patch is wrong.
Since the variable "error" is initialized as

  int error = is_delete ? -ENOENT : -ENOMEM;

at the beginning of this function, unconditionally overwriting
this variable with the return code of mutex_lock_interruptible() breaks

  if (error && !is_delete) {
  }

block of this function.

And the caller does not check if the return code is -EINTR
instead of -ENOENT or -ENOMEM.