git: 91d6afe6e2a9 - main - tcp: Sanity check of SACK holes on retransmissions

[Richard Scheffenegger]

The branch main has been updated by rscheff:

URL: 
https://cgit.FreeBSD.org/src/commit/?id=91d6afe6e2a912fd5059fc11dbeffc85474897af

commit 91d6afe6e2a912fd5059fc11dbeffc85474897af
Author:     Richard Scheffenegger <rsch...@freebsd.org>
AuthorDate: 2022-06-07 07:07:09 +0000
Commit:     Richard Scheffenegger <rsch...@freebsd.org>
CommitDate: 2022-06-07 07:38:16 +0000

    tcp: Sanity check of SACK holes on retransmissions
    
    Adding a few KASSERT() to validate sanity of sack holes, and
    bail out if sack hole is inconsistent to avoid panicing non-invariant 
builds.
    
    Reviewed By:    hselasky, glebius
    PR:             263445
    MFC after:      1 week
    Sponsored by:   NetApp, Inc.
    Differential Revision:  https://reviews.freebsd.org/D35387
---
 sys/netinet/tcp_sack.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/sys/netinet/tcp_sack.c b/sys/netinet/tcp_sack.c
index c38b9dd1d006..c1bbf65a0770 100644
--- a/sys/netinet/tcp_sack.c
+++ b/sys/netinet/tcp_sack.c
@@ -965,6 +965,18 @@ tcp_sack_output(struct tcpcb *tp, int *sack_bytes_rexmt)
                }
        }
 out:
+       KASSERT(SEQ_LT(hole->start, hole->end), ("%s: hole.start >= hole.end", 
__func__));
+       KASSERT(SEQ_LT(hole->start, tp->snd_fack), ("%s: hole.start >= 
snd.fack", __func__));
+       KASSERT(SEQ_LT(hole->end, tp->snd_fack), ("%s: hole.end >= snd.fack", 
__func__));
+       KASSERT(SEQ_LT(hole->rxmit, tp->snd_fack), ("%s: hole.rxmit >= 
snd.fack", __func__));
+       if (SEQ_GEQ(hole->start, hole->end) ||
+           SEQ_GEQ(hole->start, tp->snd_fack) ||
+           SEQ_GEQ(hole->end, tp->snd_fack) ||
+           SEQ_GEQ(hole->rxmit, tp->snd_fack)) {
+               log(LOG_CRIT,"tcp: invalid SACK hole (%u-%u,%u) vs fwd ack %u, 
ignoring.\n",
+                               hole->start, hole->end, hole->rxmit, 
tp->snd_fack);
+               return (NULL);
+       }
        return (hole);
 }