Commit 556637cd authored Apr 28, 2008 by Johannes Weiner Committed by Linus Torvalds Apr 28, 2008

mm: fix possible off-by-one in walk_pte_range()

After the loop in walk_pte_range() pte might point to the first address after
the pmd it walks.  The pte_unmap() is then applied to something bad.

Spotted by Roel Kluin and Andreas Schwab.

Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Cc: Roel Kluin <12o3l@tiscali.nl>
Cc: Andreas Schwab <schwab@suse.de>
Acked-by: Matt Mackall <mpm@selenic.com>
Acked-by: Mikael Pettersson <mikpe@it.uu.se>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent f022bfd5

mm/pagewalk.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -9,11 +9,15 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
		int err = 0;

		pte = pte_offset_map(pmd, addr);
		do {
		for (;;) {
		err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, private);
		if (err)
		break;
		} while (pte++, addr += PAGE_SIZE, addr != end);
		addr += PAGE_SIZE;
		if (addr == end)
		break;
		pte++;
		}

		pte_unmap(pte);
		return err;

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