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[95.117.45.49]) by smtp.gmail.com with ESMTPSA id t187sm13327318wma.16.2019.11.17.10.01.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 17 Nov 2019 10:01:18 -0800 (PST) Cc: mtk.manpages@gmail.com, adrian@lisas.de, akpm@linux-foundation.org, arnd@arndb.de, avagin@gmail.com, christian.brauner@ubuntu.com, dhowells@redhat.com, fweimer@redhat.com, jannh@google.com, keescook@chromium.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-man@vger.kernel.org, mingo@elte.hu, oleg@redhat.com, xemul@virtuozzo.com Subject: Re: [PATCH 2/3] clone.2: Check for MAP_FAILED not NULL on mmap() To: Christian Brauner References: <20191116114114.7066-1-christian@brauner.io> <20191116114114.7066-2-christian@brauner.io> From: "Michael Kerrisk (man-pages)" Message-ID: Date: Sun, 17 Nov 2019 19:01:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20191116114114.7066-2-christian@brauner.io> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/16/19 12:41 PM, Christian Brauner wrote: > From: Christian Brauner > > 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 > --- > 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/