linux-kernel - Re: [PATCH v3 1/5] lib/pci_iomap.c: fix cleanup bugs in pci

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Message-Id: <d20acea3-34fe-4c36-bfe2-323ece39db66@app.fastmail.com>
Date:   Mon, 04 Dec 2023 14:35:55 +0100
From:   "Arnd Bergmann" <arnd@...db.de>
To:     "Philipp Stanner" <pstanner@...hat.com>,
        "Bjorn Helgaas" <bhelgaas@...gle.com>,
        "Hanjun Guo" <guohanjun@...wei.com>, "Neil Brown" <neilb@...e.de>,
        "Kent Overstreet" <kent.overstreet@...il.com>,
        "Jakub Kicinski" <kuba@...nel.org>,
        "Niklas Schnelle" <schnelle@...ux.ibm.com>,
        "Uladzislau Koshchanka" <koshchanka@...il.com>,
        "John Sanpe" <sanpeqf@...il.com>,
        "Dave Jiang" <dave.jiang@...el.com>,
        "Masami Hiramatsu" <mhiramat@...nel.org>,
        "Kees Cook" <keescook@...omium.org>,
        "David Gow" <davidgow@...gle.com>,
        "Herbert Xu" <herbert@...dor.apana.org.au>,
        "Shuah Khan" <skhan@...uxfoundation.org>,
        "wuqiang.matt" <wuqiang.matt@...edance.com>,
        "Yury Norov" <yury.norov@...il.com>,
        "Jason Baron" <jbaron@...mai.com>,
        "Andrew Morton" <akpm@...ux-foundation.org>,
        "Ben Dooks" <ben.dooks@...ethink.co.uk>,
        "Danilo Krummrich" <dakr@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        Linux-Arch <linux-arch@...r.kernel.org>, stable@...r.kernel.org,
        "Arnd Bergmann" <arnd@...nel.org>
Subject: Re: [PATCH v3 1/5] lib/pci_iomap.c: fix cleanup bugs in pci_iounmap()

On Mon, Dec 4, 2023, at 13:38, Philipp Stanner wrote:
> pci_iounmap() in lib/pci_iomap.c is supposed to check whether an address
> is within ioport-range IF the config specifies that ioports exist. If
> so, the port should be unmapped with ioport_unmap(). If not, it's a
> generic MMIO address that has to be passed to iounmap().
>
> The bugs are:
>   1. ioport_unmap() is missing entirely, so this function will never
>      actually unmap a port.
>   2. the #ifdef for the ioport-ranges accidentally also guards
>      iounmap(), potentially compiling an empty function. This would
>      cause the mapping to be leaked.
>
> Implement the missing call to ioport_unmap().
>
> Move the guard so that iounmap() will always be part of the function.
>
> CC: <stable@...r.kernel.org> # v5.15+
> Fixes: 316e8d79a095 ("pci_iounmap'2: Electric Boogaloo: try to make 
> sense of it all")
> Reported-by: Danilo Krummrich <dakr@...hat.com>
> Suggested-by: Arnd Bergmann <arnd@...nel.org>
> Signed-off-by: Philipp Stanner <pstanner@...hat.com>
> ---
> In case someone wants to look into that and provide patches for kernels
> older than v5.15:
> Note that this patch only applies to v5.15+ – the leaks, however, are
> older. I went through the log briefly and it seems f5810e5c32923 already
> contains them in asm-generic/io.h.

Reviewed-by: Arnd Bergmann <arnd@...db.de>