Re: [RFC PATCH 1/5] kasan: do not open-code addr_has_shadow

On Fri, Feb 15, 2019 at 1:12 AM Andrew Donnellan
[off-list ref] wrote:

On 15/2/19 11:04 am, Daniel Axtens wrote:

quoted

We have a couple of places checking for the existence of a shadow
mapping for an address by open-coding the inverse of the check in
addr_has_shadow.

Replace the open-coded versions with the helper. This will be
needed in future to allow architectures to override the layout
of the shadow mapping.

Signed-off-by: Daniel Axtens <redacted>

Reviewed-by: Andrew Donnellan <redacted>

Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

quoted

---
  mm/kasan/generic.c | 3 +--
  mm/kasan/tags.c    | 3 +--
  2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index ccb6207276e3..ffc64a9a97a5 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c

@@ -173,8 +173,7 @@ static __always_inline void check_memory_region_inline(unsigned long addr,
      if (unlikely(size == 0))
              return;

-     if (unlikely((void *)addr <
-             kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
+     if (unlikely(!addr_has_shadow((void *)addr))) {
              kasan_report(addr, size, write, ret_ip);
              return;
      }

diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 0777649e07c4..bc759f8f1c67 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c

@@ -109,8 +109,7 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
              return;

      untagged_addr = reset_tag((const void *)addr);
-     if (unlikely(untagged_addr <
-                     kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
+     if (unlikely(!addr_has_shadow(untagged_addr))) {
              kasan_report(addr, size, write, ret_ip);
              return;
      }

--
Andrew Donnellan              OzLabs, ADL Canberra
andrew.donnellan@au1.ibm.com  IBM Australia Limited

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