git: dbfd8660a96d - stable/12 - bridgestp: validate timer values in config BPDU

[Kristof Provost]

The branch stable/12 has been updated by kp:

URL: https://cgit.FreeBSD.org/src/commit/?id=dbfd8660a96df693b66e9f13c70ca4302d2bfa84

commit dbfd8660a96df693b66e9f13c70ca4302d2bfa84
Author:     Jonah Caplan <jcaplan at blackberry.com>
AuthorDate: 2021-04-15 09:28:42 +0000
Commit:     Kristof Provost <kp at FreeBSD.org>
CommitDate: 2021-05-18 12:17:46 +0000

    bridgestp: validate timer values in config BPDU
    
    IEEE Std 802.1D-2004 Section 17.14 defines permitted ranges for timers.
    Incoming BPDU messages should be checked against the permitted ranges.
    The rest of 17.14 appears to be enforced already.
    
    PR:             254924
    Reviewed by:    kp, donner
    Differential Revision:  https://reviews.freebsd.org/D29782
    
    (cherry picked from commit 0e4025bffa2bab3461b72b40d0b1468722ff76e6)
---
 sys/net/bridgestp.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/sys/net/bridgestp.c b/sys/net/bridgestp.c
index 4be8e2f20819..9528cd92646a 100644
--- a/sys/net/bridgestp.c
+++ b/sys/net/bridgestp.c
@@ -594,6 +594,23 @@ bstp_received_bpdu(struct bstp_state *bs, struct bstp_port *bp,
 			return;
 	}
 
+	/* range checks */
+	if (cu->cu_message_age >= cu->cu_max_age) {
+		return;
+	}
+	if (cu->cu_max_age < BSTP_MIN_MAX_AGE ||
+	    cu->cu_max_age > BSTP_MAX_MAX_AGE) {
+		return;
+	}
+	if (cu->cu_forward_delay < BSTP_MIN_FORWARD_DELAY ||
+	    cu->cu_forward_delay > BSTP_MAX_FORWARD_DELAY) {
+		return;
+	}
+	if (cu->cu_hello_time < BSTP_MIN_HELLO_TIME ||
+	    cu->cu_hello_time > BSTP_MAX_HELLO_TIME) {
+		return;
+	}
+
 	type = bstp_pdu_rcvtype(bp, cu);
 
 	switch (type) {