From: Will Deacon Date: Fri, 16 Nov 2012 22:15:00 +0000 (-0800) Subject: mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=498c2280212327858e521e9d21345d4cc2637f54;p=openwrt%2Fstaging%2Fblogic.git mm: highmem: don't treat PKMAP_ADDR(LAST_PKMAP) as a highmem address kmap_to_page returns the corresponding struct page for a virtual address of an arbitrary mapping. This works by checking whether the address falls in the pkmap region and using the pkmap page tables instead of the linear mapping if appropriate. Unfortunately, the bounds checking means that PKMAP_ADDR(LAST_PKMAP) is incorrectly treated as a highmem address and we can end up walking off the end of pkmap_page_table and subsequently passing junk to pte_page. This patch fixes the bound check to stay within the pkmap tables. Signed-off-by: Will Deacon Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/mm/highmem.c b/mm/highmem.c index d517cd16a6eb..2da13a5c50e2 100644 --- a/mm/highmem.c +++ b/mm/highmem.c @@ -98,7 +98,7 @@ struct page *kmap_to_page(void *vaddr) { unsigned long addr = (unsigned long)vaddr; - if (addr >= PKMAP_ADDR(0) && addr <= PKMAP_ADDR(LAST_PKMAP)) { + if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) { int i = (addr - PKMAP_ADDR(0)) >> PAGE_SHIFT; return pte_page(pkmap_page_table[i]); }