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authorMarco Elver <elver@google.com>2021-05-04 18:40:18 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-05-05 11:27:27 -0700
commit94868a1e127bbe0e03a4467f27196cd668cbc344 (patch)
treec2e4043df74a4ca224270c4f8ab3772e89fa7007
parent0c4ff27a0e541bcee167612fc9065623d75314a3 (diff)
downloadlinux-94868a1e127bbe0e03a4467f27196cd668cbc344.tar.gz
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.c1
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;
}