From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Michel Lespinasse <walken@google.com>,
Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org, PaX Team <pageexec@freemail.hu>,
Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH] mm: fix use-after-free in sys_remap_file_pages
Date: Fri, 13 Dec 2013 10:24:27 +0400 [thread overview]
Message-ID: <20131213062427.GH8167@moon> (raw)
In-Reply-To: <20131212224118.17a951c2@annuminas.surriel.com>
On Thu, Dec 12, 2013 at 10:41:18PM -0500, Rik van Riel wrote:
>
> If the vma has been freed by the time the code jumps to the
> out label (because it was freed by a function called from
> mmap_region), surely it will also already have been freed
> by the time this patch dereferences it?
>
> Also, setting vma = NULL to avoid the if (vma) branch at
> the out: label is unnecessarily obfuscated. Lets make things
> clear by documenting what is going on, and having a label
> after that dereference.
This patch is a bit easier to read, at least for me. And if
I understand the code flow right, the issue is due to
remap_file_pages -> mmap_region -> find_vma_links -> do_munmap.
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WARNING: multiple messages have this Message-ID (diff)
From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: Kees Cook <keescook@chromium.org>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Michel Lespinasse <walken@google.com>,
Hugh Dickins <hughd@google.com>,
linux-mm@kvack.org, PaX Team <pageexec@freemail.hu>,
Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH] mm: fix use-after-free in sys_remap_file_pages
Date: Fri, 13 Dec 2013 10:24:27 +0400 [thread overview]
Message-ID: <20131213062427.GH8167@moon> (raw)
In-Reply-To: <20131212224118.17a951c2@annuminas.surriel.com>
On Thu, Dec 12, 2013 at 10:41:18PM -0500, Rik van Riel wrote:
>
> If the vma has been freed by the time the code jumps to the
> out label (because it was freed by a function called from
> mmap_region), surely it will also already have been freed
> by the time this patch dereferences it?
>
> Also, setting vma = NULL to avoid the if (vma) branch at
> the out: label is unnecessarily obfuscated. Lets make things
> clear by documenting what is going on, and having a label
> after that dereference.
This patch is a bit easier to read, at least for me. And if
I understand the code flow right, the issue is due to
remap_file_pages -> mmap_region -> find_vma_links -> do_munmap.
next prev parent reply other threads:[~2013-12-13 6:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-12 22:07 [PATCH] mm: fix use-after-free in sys_remap_file_pages Kees Cook
2013-12-12 22:07 ` Kees Cook
2013-12-13 3:41 ` Rik van Riel
2013-12-13 3:41 ` Rik van Riel
2013-12-13 6:24 ` Cyrill Gorcunov [this message]
2013-12-13 6:24 ` Cyrill Gorcunov
2013-12-13 11:10 ` PaX Team
2013-12-13 11:10 ` PaX Team
2013-12-13 14:43 ` [PATCH -v2] " Rik van Riel
2013-12-13 14:43 ` Rik van Riel
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