When passed a zero length skmsg tls_push_record() causes a NULL ptr
deref. To resolve for fixes do a simple length check at start of
routine.
To create this case a user can create a BPF program to pop all the
data off the message then return SK_PASS. Its not a very practical
or useful thing to do so we mark it unlikely.
Fixes: d3b18ad31f93d ("tls: add bpf support to sk_msg handling")
Signed-off-by: John Fastabend <john.fastabend@xxxxxxxxx>
---
net/tls/tls_sw.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/tls/tls_sw.c b/net/tls/tls_sw.c
index 21c7725d17ca..0326e916ab01 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -680,6 +680,9 @@ static int tls_push_record(struct sock *sk, int flags,
msg_pl = &rec->msg_plaintext;
msg_en = &rec->msg_encrypted;
+ if (unlikely(!msg_pl->sg.size))
+ return 0;
+
split_point = msg_pl->apply_bytes;
split = split_point && split_point < msg_pl->sg.size;
if (unlikely((!split &&
