netdev - [PATCH net 5/5] tls: don't decrypt the next record if it's of a different type

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Message-Id: <be8519564777b3a40eeb63002041576f9009a733.1694018970.git.sd@queasysnail.net>
Date: Wed,  6 Sep 2023 19:08:35 +0200
From: Sabrina Dubroca <sd@...asysnail.net>
To: netdev@...r.kernel.org
Cc: Sabrina Dubroca <sd@...asysnail.net>,
	Dave Watson <davejwatson@...com>,
	Jakub Kicinski <kuba@...nel.org>,
	Vakul Garg <vakul.garg@....com>,
	Boris Pismenny <borisp@...dia.com>,
	John Fastabend <john.fastabend@...il.com>
Subject: [PATCH net 5/5] tls: don't decrypt the next record if it's of a different type

If the next record is of a different type, we won't copy it to
userspace in this round, tls_record_content_type will stop us just
after decryption. Skip decryption until the next recvmsg() call.

This fixes a use-after-free when a data record is decrypted
asynchronously but doesn't fill the userspace buffer, and the next
record is non-data, for example in the bad_cmsg selftest.

Fixes: c0ab4732d4c6 ("net/tls: Do not use async crypto for non-data records")
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 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 f80a2ea1dd7e..86b835b15872 100644
--- a/net/tls/tls_sw.c
+++ b/net/tls/tls_sw.c
@@ -2010,6 +2010,9 @@ int tls_sw_recvmsg(struct sock *sk,
 		else
 			darg.async = false;
 
+		if (ctx->async_capable && control && tlm->control != control)
+			goto recv_end;
+
 		err = tls_rx_one_record(sk, msg, &darg);
 		if (err < 0) {
 			tls_err_abort(sk, -EBADMSG);
-- 
2.40.1