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Subject: [BUG] binfmt_elf: get_user() called in vma_dump_size() after
	set_fs(KERNEL_DS)
From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
To: Roland McGrath <roland@redhat.com>
Cc: linux-kernel@vger.kernel.org, Martin Schwidefsky <schwidefsky@de.ibm.com>,
       Heiko Carstens <heiko.carstens@de.ibm.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Linus Torvalds <torvalds@linux-foundation.org>
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Date: Fri, 06 Feb 2009 18:10:35 +0100
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Hi,

elf_core_dump() does a set_fs(KERNEL_DS) and then calls vma_dump_size(),
which uses get_user() to check for an ELF header at vma->vm_start in the
user mapping. This is a bug because vm_start is a user virtual address and
get_user() will fail or even read from a kernel address (KERNEL_DS).

Maybe a get_user_pages() should be used to get the user data, or a temporary
set_fs(USER_DS)?

--
Gerald