Re: [PATCH v5 22/38] kmsan: net: check the value of skb before sending it to the network

[Alexander Potapenko <glider@google.com>]

On Wed, Mar 25, 2020 at 5:14 PM <glider@google.com> wrote:
>
> Calling kmsan_check_skb() lets KMSAN check the bytes to be transferred
> over the network for being initialized.
>
> Signed-off-by: Alexander Potapenko <glider@google.com>
> To: Alexander Potapenko <glider@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: Petr Mladek <pmladek@suse.com>
> Cc: Vegard Nossum <vegard.nossum@oracle.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Marco Elver <elver@google.com>
> Cc: Andrey Konovalov <andreyknvl@google.com>
> Cc: linux-mm@kvack.org
>
> ---
>
> This patch was previously called "kmsan: call KMSAN hooks where needed"
>
> v4:
>  - split this patch away
>
> Change-Id: Iff48409dc50341d59e355ce3ec11d4722f0799e2
> ---
>  net/sched/sch_generic.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
> index 2efd5b61acef1..4b2cc309bb1e3 100644
> --- a/net/sched/sch_generic.c
> +++ b/net/sched/sch_generic.c
> @@ -11,6 +11,7 @@
>  #include <linux/module.h>
>  #include <linux/types.h>
>  #include <linux/kernel.h>
> +#include <linux/kmsan-checks.h>
>  #include <linux/sched.h>
>  #include <linux/string.h>
>  #include <linux/errno.h>
> @@ -654,6 +655,7 @@ static struct sk_buff *pfifo_fast_dequeue(struct Qdisc *qdisc)
>         } else {
>                 WRITE_ONCE(qdisc->empty, true);
>         }
> +       kmsan_check_skb(skb);

I'm going to drop this patch from v6 to reduce its size. We haven't
found any bugs using this check, so something is probably going wrong
here.