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Date:   Sun, 26 Nov 2023 15:56:46 -0800
From:   John Fastabend <john.fastabend@gmail.com>
To:     Jann Horn <jannh@google.com>, Boris Pismenny <borisp@nvidia.com>,
        John Fastabend <john.fastabend@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "David S. Miller" <davem@davemloft.net>
Cc:     David Howells <dhowells@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Message-ID: <6563db3e1d1ef_68d9b208cf@john.notmuch>
In-Reply-To: <CAG48ez3dn7CAfTmfziBUd_aFfcM1LOYsUuYrKykZAvTv=AAodg@mail.gmail.com>
References: <20231122214447.675768-1-jannh@google.com>
 <CAG48ez3dn7CAfTmfziBUd_aFfcM1LOYsUuYrKykZAvTv=AAodg@mail.gmail.com>
Subject: Re: [PATCH net] tls: fix NULL deref on tls_sw_splice_eof() with empty
 record
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Jann Horn wrote:
> On Wed, Nov 22, 2023 at 10:44=E2=80=AFPM Jann Horn <jannh@google.com> w=
rote:
> > syzkaller discovered that if tls_sw_splice_eof() is executed as part =
of
> > sendfile() when the plaintext/ciphertext sk_msg are empty, the send p=
ath
> > gets confused because the empty ciphertext buffer does not have enoug=
h
> > space for the encryption overhead. This causes tls_push_record() to g=
o on
> > the `split =3D true` path (which is only supposed to be used when int=
eracting
> > with an attached BPF program), and then get further confused and hit =
the
> > tls_merge_open_record() path, which then assumes that there must be a=
t
> > least one populated buffer element, leading to a NULL deref.
> =

> Ah, and in case you're looking for the corresponding syzkaller report,
> you can find that at
> <https://lore.kernel.org/all/000000000000347a250608e8a4d1@google.com/T/=
>.

I'm a bit slow, but looks good to me as well. Thanks a lot.

Acked-by: John Fastabend <john.fastabend@gmail.com>=