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authorWill Deacon <will.deacon@arm.com>2012-11-16 14:15:00 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-11-16 14:33:04 -0800
commit498c2280212327858e521e9d21345d4cc2637f54 (patch)
tree41263d573286cae19d99083d57165ffa0412b9e7
parent96710098ee124951ff2fed7cd8406da92aad011a (diff)
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 <will.deacon@arm.com> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/highmem.c2
1 files changed, 1 insertions, 1 deletions
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]);
}