diff options
| author | Andrey Konovalov <andreyknvl@google.com> | 2018-12-28 00:30:57 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:44 -0800 |
| commit | 2813b9c0296259fb11e75c839bab2d958ba4f96c (patch) | |
| tree | 4f174c60d6f189977d74053b118f8f820ab689f1 /include/linux/page-flags-layout.h | |
| parent | 41eea9cd239c5b3fff726894f85c97f60e5799a3 (diff) | |
kasan, mm, arm64: tag non slab memory allocated via pagealloc
Tag-based KASAN doesn't check memory accesses through pointers tagged with
0xff. When page_address is used to get pointer to memory that corresponds
to some page, the tag of the resulting pointer gets set to 0xff, even
though the allocated memory might have been tagged differently.
For slab pages it's impossible to recover the correct tag to return from
page_address, since the page might contain multiple slab objects tagged
with different values, and we can't know in advance which one of them is
going to get accessed. For non slab pages however, we can recover the tag
in page_address, since the whole page was marked with the same tag.
This patch adds tagging to non slab memory allocated with pagealloc. To
set the tag of the pointer returned from page_address, the tag gets stored
to page->flags when the memory gets allocated.
Link: http://lkml.kernel.org/r/d758ddcef46a5abc9970182b9137e2fbee202a2c.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/page-flags-layout.h')
| -rw-r--r-- | include/linux/page-flags-layout.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h index 7ec86bf31ce4..1dda31825ec4 100644 --- a/include/linux/page-flags-layout.h +++ b/include/linux/page-flags-layout.h @@ -82,6 +82,16 @@ #define LAST_CPUPID_WIDTH 0 #endif +#ifdef CONFIG_KASAN_SW_TAGS +#define KASAN_TAG_WIDTH 8 +#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH+LAST_CPUPID_WIDTH+KASAN_TAG_WIDTH \ + > BITS_PER_LONG - NR_PAGEFLAGS +#error "KASAN: not enough bits in page flags for tag" +#endif +#else +#define KASAN_TAG_WIDTH 0 +#endif + /* * We are going to use the flags for the page to node mapping if its in * there. This includes the case where there is no node, so it is implicit. |