Re: [PATCH net] tls: fix NULL deref on tls_sw_splice_eof() with empty record

[John Fastabend]

Jann Horn wrote:
> On Wed, Nov 22, 2023 at 10:44 PM Jann Horn <jannh@xxxxxxxxxx> wrote:
> > syzkaller discovered that if tls_sw_splice_eof() is executed as part of
> > sendfile() when the plaintext/ciphertext sk_msg are empty, the send path
> > gets confused because the empty ciphertext buffer does not have enough
> > space for the encryption overhead. This causes tls_push_record() to go on
> > the `split = true` path (which is only supposed to be used when interacting
> > 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 at
> > 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@xxxxxxxxxx/T/>.

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

Acked-by: John Fastabend <john.fastabend@xxxxxxxxx>