[PATCH] Don't map the same page too much
Refuse to install a page into a mapping if the mapping count is already
ridiculously large.
You probably cannot trigger this on 32-bit architectures, but on a
64-bit setup we should protect against it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/fremap.c b/mm/fremap.c
index 3235fb7..ab23a06 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -89,6 +89,9 @@
size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (!page->mapping || page->index >= size)
goto err_unlock;
+ err = -ENOMEM;
+ if (page_mapcount(page) > INT_MAX/2)
+ goto err_unlock;
zap_pte(mm, vma, addr, pte);