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From a0afe035cbca26f8c74b670a8c2a20b3d9c2294b Mon Sep 17 00:00:00 2001
From: Arne Schwabe <arne@rfc2549.org>
Date: Fri, 27 Oct 2023 14:19:37 +0200
Subject: [PATCH] Fix using to_link buffer after freed
When I refactored the tls_state_change method in
9a7b95fda5 I accidentally changed a break into
a return true while it should return a false.
The code here is extremely fragile in the sense
that it assumes that settings a keystate to S_ERROR
cannot have any outgoing buffer or we will have a
use after free. The previous break and now restored
return false ensure this by skipping any further
tls_process_state loops that might set to ks->S_ERROR
and ensure that the to_link is sent out and cleared
before having more loops in tls_state_change.
CVE: 2023-46850
This affects everyone, even with tls-auth/tls-crypt enabled.
Change-Id: I2a0f1c665d992da8e24a421ff0ddcb40f7945ea8
Signed-off-by: Arne Schwabe <arne@rfc2549.org>
Acked-by: David Sommerseth <davids@openvpn.net>
Acked-by: Heiko Hund <heiko@ist.eigentlich.net>
Message-Id: <20231108124947.76816-3-gert@greenie.muc.de>
URL: https://www.mail-archive.com/search?l=mid&q=20231108124947.76816-3-gert@greenie.muc.de
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit 57a5cd1e12f193927c9b7429f8778fec7e04c50a)
---
src/openvpn/ssl.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
index e15f951d6a0..cee4afe19f3 100644
--- a/src/openvpn/ssl.c
+++ b/src/openvpn/ssl.c
@@ -2903,7 +2903,13 @@ tls_process_state(struct tls_multi *multi,
CONTROL_SEND_ACK_MAX, true);
*to_link = b;
dmsg(D_TLS_DEBUG, "Reliable -> TCP/UDP");
- return true;
+
+ /* This changed the state of the outgoing buffer. In order to avoid
+ * running this function again/further and invalidating the key_state
+ * buffer and accessing the buffer that is now in to_link after it being
+ * freed for a potential error, we shortcircuit exiting of the outer
+ * process here. */
+ return false;
}
/* Write incoming ciphertext to TLS object */
|
