linux-kernel - Re: [PATCH] usercopy: Add parentheses around assignment in test_copy_struct_from

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Date:   Thu, 3 Oct 2019 21:13:18 +0200
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Aleksa Sarai <cyphar@...har.com>,
        Kees Cook <keescook@...omium.org>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] usercopy: Add parentheses around assignment in
 test_copy_struct_from_user

On Thu, Oct 03, 2019 at 10:11:21AM -0700, Nathan Chancellor wrote:
> Clang warns:
> 
> lib/test_user_copy.c:96:10: warning: using the result of an assignment
> as a condition without parentheses [-Wparentheses]
>         if (ret |= test(umem_src == NULL, "kmalloc failed"))
>             ~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> lib/test_user_copy.c:96:10: note: place parentheses around the
> assignment to silence this warning
>         if (ret |= test(umem_src == NULL, "kmalloc failed"))
>                 ^
>             (                                              )
> lib/test_user_copy.c:96:10: note: use '!=' to turn this compound
> assignment into an inequality comparison
>         if (ret |= test(umem_src == NULL, "kmalloc failed"))
>                 ^~
>                 !=
> 
> Add the parentheses as it suggests because this is intentional.
> 
> Fixes: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper")
> Link: https://github.com/ClangBuiltLinux/linux/issues/731
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

Applied to:
https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=copy_struct_from_user

Thanks!
Christian