diff options
| author | Marco Elver <elver@google.com> | 2021-05-05 04:40:18 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-05-05 21:27:27 +0300 |
| commit | 94868a1e127bbe0e03a4467f27196cd668cbc344 (patch) | |
| tree | c2e4043df74a4ca224270c4f8ab3772e89fa7007 | |
| parent | 0c4ff27a0e541bcee167612fc9065623d75314a3 (diff) | |
| download | linux-94868a1e127bbe0e03a4467f27196cd668cbc344.tar.xz | |
kfence: zero guard page after out-of-bounds access
After an out-of-bounds accesses, zero the guard page before re-protecting
in kfence_guarded_free(). On one hand this helps make the failure mode of
subsequent out-of-bounds accesses more deterministic, but could also
prevent certain information leaks.
Link: https://lkml.kernel.org/r/20210312121653.348518-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/kfence/core.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/mm/kfence/core.c b/mm/kfence/core.c index d53c91f881a4..768dbd58170d 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -372,6 +372,7 @@ static void kfence_guarded_free(void *addr, struct kfence_metadata *meta, bool z /* Restore page protection if there was an OOB access. */ if (meta->unprotected_page) { + memzero_explicit((void *)ALIGN_DOWN(meta->unprotected_page, PAGE_SIZE), PAGE_SIZE); kfence_protect(meta->unprotected_page); meta->unprotected_page = 0; } |