Messages in this thread Patch in this message | | | Date | Wed, 8 Jun 2005 16:52:06 -0700 | From | Chris Wright <> | Subject | [patch 01/09] try_to_unmap_cluster() passes out-of-bounds pte to pte_unmap() |
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try_to_unmap_cluster() does: for (pte = pte_offset_map(pmd, address); address < end; pte++, address += PAGE_SIZE) { ... }
pte_unmap(pte);
It may take a little staring to notice, but pte can actually fall off the end of the pte page in this iteration, which makes life difficult for kmap_atomic() and the users not expecting it to BUG(). Of course, we're somewhat lucky in that arithmetic elsewhere in the function guarantees that at least one iteration is made, lest this force larger rearrangements to be made. This issue and patch also apply to non-mm mainline and with trivial adjustments, at least two related kernels.
Discovered during internal testing at Oracle.
Signed-off-by: William Irwin <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- gregkh-2.6.11.10.orig/mm/rmap.c 2005-05-16 10:51:55.000000000 -0700 +++ gregkh-2.6.11.10/mm/rmap.c 2005-05-26 22:01:49.000000000 -0700 @@ -641,7 +641,7 @@ pgd_t *pgd; pud_t *pud; pmd_t *pmd; - pte_t *pte; + pte_t *pte, *original_pte; pte_t pteval; struct page *page; unsigned long address; @@ -673,7 +673,7 @@ if (!pmd_present(*pmd)) goto out_unlock; - for (pte = pte_offset_map(pmd, address); + for (original_pte = pte = pte_offset_map(pmd, address); address < end; pte++, address += PAGE_SIZE) { if (!pte_present(*pte)) @@ -710,7 +710,7 @@ (*mapcount)--; } - pte_unmap(pte); + pte_unmap(original_pte); out_unlock: spin_unlock(&mm->page_table_lock); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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