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Subject: Re: [PATCH 2/3] clone.2: Check for MAP_FAILED not NULL on mmap()
To:     Christian Brauner <christian@brauner.io>
References: <20191116114114.7066-1-christian@brauner.io>
 <20191116114114.7066-2-christian@brauner.io>
From:   "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
Message-ID: <e94e46a1-d852-f5df-352c-592d5e0e9c6a@gmail.com>
Date:   Sun, 17 Nov 2019 19:01:18 +0100
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On 11/16/19 12:41 PM, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@ubuntu.com>
> 
> If mmap() fails it will return MAP_FAILED which according to the manpage
> is (void *)-1 not NULL.

Sigh! Bad editing on my part.

Thanks, Christian.

Patch applied.

Cheers,

Michael


> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
> ---
>  man2/clone.2 | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/man2/clone.2 b/man2/clone.2
> index 57a9eaba7..faff2ada6 100644
> --- a/man2/clone.2
> +++ b/man2/clone.2
> @@ -1628,7 +1628,7 @@ main(int argc, char *argv[])
>  
>      stack = mmap(NULL, STACK_SIZE, PROT_READ | PROT_WRITE,
>                   MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, \-1, 0);
> -    if (stack == NULL)
> +    if (stack == MAP_FAILED)
>          errExit("mmap");
>  
>      stackTop = stack + STACK_SIZE;  /* Assume stack grows downward */
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/