git: 6e298c3612da - stable/13 - tcp: prevent div by zero in cc_htcp

The branch stable/13 has been updated by rscheff:

URL: https://cgit.FreeBSD.org/src/commit/?id=6e298c3612da3d04a75d380cf457774cb1a25a47

commit 6e298c3612da3d04a75d380cf457774cb1a25a47
Author:     Richard Scheffenegger <rscheff@FreeBSD.org>
AuthorDate: 2024-02-24 15:35:23 +0000
Commit:     Richard Scheffenegger <rscheff@FreeBSD.org>
CommitDate: 2024-02-28 00:21:47 +0000

    tcp: prevent div by zero in cc_htcp
    
    Make sure the divident is at least one. While cwnd should
    never be smaller than t_maxseg, this can happen during
    Path MTU Discovery, or when TCP options are considered
    in other parts of the stack.
    
    PR:                     276674
    MFC after:              3 days
    Reviewed By:            tuexen, #transport
    Sponsored by:           NetApp, Inc.
    Differential Revision:  https://reviews.freebsd.org/D43797
    
    (cherry picked from commit 38983d40c18ec5705dcba19ac320b86c5efe8e7e)
---
 sys/netinet/cc/cc_htcp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sys/netinet/cc/cc_htcp.c b/sys/netinet/cc/cc_htcp.c
index 70ac0bebffe9..6568c5ae672e 100644
--- a/sys/netinet/cc/cc_htcp.c
+++ b/sys/netinet/cc/cc_htcp.c
@@ -226,9 +226,9 @@ htcp_ack_received(struct cc_var *ccv, uint16_t type)
 				 * per RTT.
 				 */
 				CCV(ccv, snd_cwnd) += (((htcp_data->alpha <<
-				    HTCP_SHIFT) / (CCV(ccv, snd_cwnd) /
-				    CCV(ccv, t_maxseg))) * CCV(ccv, t_maxseg))
-				    >> HTCP_SHIFT;
+				    HTCP_SHIFT) / (max(1,
+				    CCV(ccv, snd_cwnd) / CCV(ccv, t_maxseg)))) *
+				    CCV(ccv, t_maxseg))  >> HTCP_SHIFT;
 		}
 	}
 }