From: Andrew Morton <akpm@linux-foundation.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: linux-mm@kvack.org, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH, RESEND] ipc/shm: fix crash if CONFIG_SHMEM is not set
Date: Mon, 12 Sep 2016 15:21:48 -0700 [thread overview]
Message-ID: <20160912152148.0b8ef73e32bbc28104356bb7@linux-foundation.org> (raw)
In-Reply-To: <20160912102704.140442-1-kirill.shutemov@linux.intel.com>
On Mon, 12 Sep 2016 13:27:04 +0300 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> wrote:
> Commit c01d5b300774 makes use of shm_get_unmapped_area() in
> shm_file_operations() unconditional to CONFIG_MMU.
>
> As Tony Battersby pointed this can lead NULL-pointer dereference on
> machine with CONFIG_MMU=y and CONFIG_SHMEM=n. In this case ipc/shm is
> backed by ramfs which doesn't provide f_op->get_unmapped_area for
> configurations with MMU.
>
> The solution is to provide dummy f_op->get_unmapped_area for ramfs when
> CONFIG_MMU=y, which just call current->mm->get_unmapped_area().
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Reported-and-Tested-by: Tony Battersby <tonyb@cybernetics.com>
> Fixes: c01d5b300774 ("shmem: get_unmapped_area align huge page")
I'll add
Cc: <stable@vger.kernel.org> [4.7.x]
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prev parent reply other threads:[~2016-09-12 22:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-12 10:27 Kirill A. Shutemov
2016-09-12 22:21 ` Andrew Morton [this message]
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