2022-12-22 23:04:21

by Deepak R Varma

Subject: [PATCH] w1: Use kfree_sensitive to clear sensitive information

Replace combination of 'memset(0) + kfree()' by kfree_sensitive() as it
prevents compiler from optimizing away from zeroing out memory at the
end of a scope. kfree_sensitive() is also safe in case the memory
pointer turns out to be null, which simply gets ignored.

Issue identified using kfree_sensitive.cocci coccinelle semantic patch.

Signed-off-by: Deepak R Varma <[email protected]>
---
Note: proposed change is compile tested only.

drivers/w1/w1.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index f2ae2e563dc5..e08467e08b73 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -73,8 +73,7 @@ static void w1_master_release(struct device *dev)
struct w1_master *md = dev_to_w1_master(dev);

dev_dbg(dev, "%s: Releasing %s.\n", __func__, md->name);
- memset(md, 0, sizeof(struct w1_master) + sizeof(struct w1_bus_master));
- kfree(md);
+ kfree_sensitive(md);
}

static void w1_slave_release(struct device *dev)
@@ -805,9 +804,10 @@ int w1_unref_slave(struct w1_slave *sl)
w1_family_notify(BUS_NOTIFY_DEL_DEVICE, sl);
device_unregister(&sl->dev);
#ifdef DEBUG
- memset(sl, 0, sizeof(*sl));
- #endif
+ kfree_sensitive(sl);
+ #else
kfree(sl);
+ #endif
}
atomic_dec(&dev->refcnt);
mutex_unlock(&dev->list_mutex);
--
2.34.1

2023-01-07 20:25:29

by Deepak R Varma

Subject: Re: [PATCH] w1: Use kfree_sensitive to clear sensitive information

On Fri, Dec 23, 2022 at 04:09:22AM +0530, Deepak R Varma wrote:
> Replace combination of 'memset(0) + kfree()' by kfree_sensitive() as it
> prevents compiler from optimizing away from zeroing out memory at the
> end of a scope. kfree_sensitive() is also safe in case the memory
> pointer turns out to be null, which simply gets ignored.
>
> Issue identified using kfree_sensitive.cocci coccinelle semantic patch.
>
> Signed-off-by: Deepak R Varma <[email protected]>
> ---

Hello,
Requesting a review and feedback on this patch proposal.

Thank you,
./drv

2023-01-22 19:50:58

by Deepak R Varma

Subject: Re: [PATCH] w1: Use kfree_sensitive to clear sensitive information

On Sun, Jan 08, 2023 at 01:41:18AM +0530, Deepak R Varma wrote:
> On Fri, Dec 23, 2022 at 04:09:22AM +0530, Deepak R Varma wrote:
> > Replace combination of 'memset(0) + kfree()' by kfree_sensitive() as it
> > prevents compiler from optimizing away from zeroing out memory at the
> > end of a scope. kfree_sensitive() is also safe in case the memory
> > pointer turns out to be null, which simply gets ignored.
> >
> > Issue identified using kfree_sensitive.cocci coccinelle semantic patch.
> >
> > Signed-off-by: Deepak R Varma <[email protected]>
> > ---
>
> Hello,
> Requesting a review and feedback on this patch proposal.

Hello,
Requesting a review and feedback on this patch proposal please.

Thank you,
./drv

>
> Thank you,
> ./drv