linux-kernel - Re: [PATCH v3] seq_file: fix NULL pointer arithmetic warning

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Message-ID: <YflgH+uaoMJTlUoK@casper.infradead.org>
Date:   Tue, 1 Feb 2022 16:30:23 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Maíra Canal <maira.canal@....br>
Cc:     gregkh@...uxfoundation.org, tj@...nel.org, viro@...iv.linux.org.uk,
        nathan@...nel.org, ndesaulniers@...gle.com,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        llvm@...ts.linux.dev
Subject: Re: [PATCH v3] seq_file: fix NULL pointer arithmetic warning

On Mon, Jan 31, 2022 at 03:22:42PM -0300, Maíra Canal wrote:
> Implement conditional logic in order to replace NULL pointer arithmetic.
> 
> The use of NULL pointer arithmetic was pointed out by clang with the
> following warning:
> 
> fs/kernfs/file.c:128:15: warning: performing pointer arithmetic on a
> null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>                 return NULL + !*ppos;
>                        ~~~~ ^
> fs/seq_file.c:559:14: warning: performing pointer arithmetic on a
> null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>         return NULL + (*pos == 0);
> 
> Signed-off-by: Maíra Canal <maira.canal@....br>

Reviewed-by: Matthew Wilcox (Oracle) <willy@...radead.org>