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Commit b8107480 authored by Kirill Korotaev's avatar Kirill Korotaev Committed by Linus Torvalds
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[PATCH] do_swap_page() can map random data if swap read fails 



There is a bug in do_swap_page(): when swap page happens to be unreadable,
page filled with random data is mapped into user address space.  The fix is
to check for PageUptodate and send SIGBUS in case of error.

Signed-Off-By: default avatarKirill Korotaev <dev@sw.ru>
Signed-Off-By: default avatarAlexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Acked-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent c64610ba

mm/memory.c

+12 −5
Original line number Diff line number Diff line
@@ -1701,12 +1701,13 @@ static int do_swap_page(struct mm_struct * mm, 
	spin_lock(&mm->page_table_lock);

	page_table = pte_offset_map(pmd, address);

	if (unlikely(!pte_same(*page_table, orig_pte))) {

		pte_unmap(page_table);

		spin_unlock(&mm->page_table_lock);

		unlock_page(page);

		page_cache_release(page);

		ret = VM_FAULT_MINOR;

		goto out;

		goto out_nomap;

	}



	if (unlikely(!PageUptodate(page))) {

		ret = VM_FAULT_SIGBUS;

		goto out_nomap;

	}



	/* The page isn't present yet, go ahead with the fault. */
@@ -1741,6 +1742,12 @@ static int do_swap_page(struct mm_struct * mm, 
	spin_unlock(&mm->page_table_lock);

out:

	return ret;

out_nomap:

	pte_unmap(page_table);

	spin_unlock(&mm->page_table_lock);

	unlock_page(page);

	page_cache_release(page);

	goto out;

}



/*