[v4,1/3] mm/slab: Use memzero_explicit() in kzfree()

Message ID 20200616015718.7812-2-longman@redhat.com
State New
Headers show
Series
  • [v4,1/3] mm/slab: Use memzero_explicit() in kzfree()
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Commit Message

Waiman Long June 16, 2020, 1:57 a.m.
The kzfree() function is normally used to clear some sensitive
information, like encryption keys, in the buffer before freeing it back
to the pool. Memset() is currently used for the buffer clearing. However,
it is entirely possible that the compiler may choose to optimize away the
memory clearing especially if LTO is being used. To make sure that this
optimization will not happen, memzero_explicit(), which is introduced
in v3.18, is now used in kzfree() to do the clearing.

Fixes: 3ef0e5ba4673 ("slab: introduce kzfree()")
Cc: stable@vger.kernel.org
Signed-off-by: Waiman Long <longman@redhat.com>
---
 mm/slab_common.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Patch

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 9e72ba224175..37d48a56431d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1726,7 +1726,7 @@  void kzfree(const void *p)
 	if (unlikely(ZERO_OR_NULL_PTR(mem)))
 		return;
 	ks = ksize(mem);
-	memset(mem, 0, ks);
+	memzero_explicit(mem, ks);
 	kfree(mem);
 }
 EXPORT_SYMBOL(kzfree);