From mboxrd@z Thu Jan 1 00:00:00 1970 From: Waiman Long Subject: [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree() Date: Mon, 15 Jun 2020 21:57:16 -0400 Message-ID: <20200616015718.7812-2-longman@redhat.com> References: <20200616015718.7812-1-longman@redhat.com> Return-path: In-Reply-To: <20200616015718.7812-1-longman@redhat.com> Sender: linux-btrfs-owner@vger.kernel.org To: Andrew Morton , David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Linus Torvalds , Joe Perches , Matthew Wilcox , David Rientjes Cc: Michal Hocko , Johannes Weiner , Dan Carpenter , David Sterba , "Jason A . Donenfeld" , linux-mm@kvack.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-pm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-amlogic@lists.infradead.org, linux-mediatek@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-ppp@vger.kernel.org, wireguard@lists.zx2c4.com, linux-wireless@vger.kernel.org, devel@driverdev.osuosl.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fscrypt@vger. List-Id: virtualization@lists.linuxfoundation.org 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 --- mm/slab_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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); -- 2.18.1