From: Dan Carpenter <dan.carpenter@oracle.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Waiman Long <longman@redhat.com>,
"Jason A . Donenfeld" <Jason@zx2c4.com>,
linux-btrfs@vger.kernel.org,
Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
David Sterba <dsterba@suse.cz>,
David Howells <dhowells@redhat.com>,
linux-mm@kvack.org, linux-sctp@vger.kernel.org,
keyrings@vger.kernel.org, kasan-dev@googlegroups.com,
linux-stm32@st-md-mailman.stormreply.com,
devel@driverdev.osuosl.org, linux-cifs@vger.kernel.org,
linux-scsi@vger.kernel.org, James Morris <jmorris@namei.org>,
Matthew Wilcox <willy@infradead.org>,
linux-wpan@vger.kernel.org, David Rientjes <rientjes@google.com>,
linux-pm@vger.kernel.org, ecryptfs@vger.kernel.org,
linux-fscrypt@vger.kernel.org,
linux-mediatek@lists.infradead.org,
linux-amlogic@lists.infradead.org,
virtualization@lists.linux-foundation.org,
linux-integrity@vger.kernel.org, linux-nfs@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org, linux-bluetooth@vger.kernel.org,
linux-security-module@vger.kernel.org,
target-devel@vger.kernel.org,
tipc-discussion@lists.sourceforge.net,
linux-crypto@vger.kernel.org,
Johannes Weiner <hannes@cmpxchg.org>,
Joe Perches <joe@perches.com>,
Andrew Morton <akpm@linux-foundation.org>,
linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org,
wireguard@lists.zx2c4.com, linux-ppp@vger.kernel.org
Subject: Re: [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree()
Date: Tue, 16 Jun 2020 12:08:07 +0300 [thread overview]
Message-ID: <20200616090807.GK4151@kadam> (raw)
In-Reply-To: <20200616064208.GA9499@dhcp22.suse.cz>
On Tue, Jun 16, 2020 at 08:42:08AM +0200, Michal Hocko wrote:
> On Mon 15-06-20 21:57:16, Waiman Long wrote:
> > 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>
>
> Acked-by: Michal Hocko <mhocko@suse.com>
>
> Although I am not really sure this is a stable material. Is there any
> known instance where the memset was optimized out from kzfree?
I told him to add the stable. Otherwise it will just get reported to
me again. It's a just safer to backport it before we forget.
regards,
dan carpenter
next prev parent reply other threads:[~2020-06-17 8:03 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-16 1:57 [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() Waiman Long
2020-06-16 1:57 ` [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree() Waiman Long
2020-06-16 3:30 ` Eric Biggers
2020-06-16 13:05 ` Waiman Long
2020-06-16 15:46 ` David Howells
2020-06-16 6:42 ` Michal Hocko
2020-06-16 9:08 ` Dan Carpenter [this message]
2020-06-16 1:57 ` [PATCH v4 2/3] mm, treewide: Rename kzfree() to kfree_sensitive() Waiman Long
2020-06-16 14:26 ` Dan Carpenter
2020-06-16 15:05 ` Waiman Long
2020-06-16 1:57 ` [PATCH v4 3/3] btrfs: Use kfree() in btrfs_ioctl_get_subvol_info() Waiman Long
2020-06-16 14:48 ` David Sterba
2020-06-16 15:05 ` Waiman Long
2020-06-16 18:53 ` [PATCH v4 0/3] mm, treewide: Rename kzfree() to kfree_sensitive() Joe Perches
2020-06-16 19:43 ` Waiman Long
2020-06-16 19:46 ` Jason A. Donenfeld
2020-06-16 20:01 ` Waiman Long
2020-06-16 21:14 ` Matthew Wilcox
2020-06-16 23:01 ` David Sterba
2020-06-17 0:37 ` Matthew Wilcox
2020-06-17 7:12 ` Michal Hocko
2020-06-17 11:08 ` Matthew Wilcox
2020-06-17 11:31 ` Michal Hocko
2020-06-17 12:23 ` Matthew Wilcox
2020-06-17 12:55 ` Michal Hocko
2020-06-17 8:03 ` Jo -l
2020-06-17 21:31 ` Denis Efremov
2020-06-17 23:12 ` Joe Perches
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