The patch titled
Subject: mm: prevent mapping slab pages to userspace
has been added to the -mm tree. Its filename is
mm-prevent-mapping-slab-pages-to-userspace.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-prevent-mapping-slab-pages-to-userspace.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-prevent-mapping-slab-pages-to-userspace.patch
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------------------------------------------------------
From: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Subject: mm: prevent mapping slab pages to userspace
It's never appropriate to map a page allocated by SLAB into userspace. A
buggy device driver might try this, or an attacker might be able to find a
way to make it happen.
Christoph said:
: Let's just fail the code. Currently this may work with SLUB. But SLAB
: and SLOB overlay fields with mapcount. So you would have a corrupted page
: struct if you mapped a slab page to user space.
Link: http://lkml.kernel.org/r/20190125173827.2658-1-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/memory.c~mm-prevent-mapping-slab-pages-to-userspace
+++ a/mm/memory.c
@@ -1452,7 +1452,7 @@ static int insert_page(struct vm_area_st
spinlock_t *ptl;
retval = -EINVAL;
- if (PageAnon(page))
+ if (PageAnon(page) || PageSlab(page))
goto out;
retval = -ENOMEM;
flush_dcache_page(page);
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-remove-sysctl_extfrag_handler.patch
mm-remove-redundant-test-from-find_get_pages_contig.patch
mm-prevent-mapping-slab-pages-to-userspace.patch
