git: e3e7d953323c - main - tcp: Avoid division by zero when KERN_TLS is enabled in tcp_account_for_send().

[Hans Petter Selasky]

The branch main has been updated by hselasky:

URL: https://cgit.FreeBSD.org/src/commit/?id=e3e7d953323c450dbe3ecbb21f9741f049ee3017

commit e3e7d953323c450dbe3ecbb21f9741f049ee3017
Author:     Hans Petter Selasky <hselasky at FreeBSD.org>
AuthorDate: 2021-09-15 16:03:38 +0000
Commit:     Hans Petter Selasky <hselasky at FreeBSD.org>
CommitDate: 2021-09-15 16:05:31 +0000

    tcp: Avoid division by zero when KERN_TLS is enabled in tcp_account_for_send().
    
    If the "len" variable is non-zero, we can assume that the sum of
    "tp->t_snd_rxt_bytes + tp->t_sndbytes" is also non-zero.
    
    It is also assumed that the 64-bit byte counters will never wrap around.
    
    Differential Revision:  https://reviews.freebsd.org/D31959
    Reviewed by:    gallatin, rrs and tuexen
    Found by:       "I told you so", also called hselasky
    MFC after:      1 week
    Sponsored by:   NVIDIA Networking
---
 sys/netinet/tcp_var.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index 64e954cf4ad5..c26f503f4a1d 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -1155,7 +1155,7 @@ tcp_account_for_send(struct tcpcb *tp, uint32_t len, uint8_t is_rxt,
 		tp->t_sndbytes += len;
 
 #ifdef KERN_TLS
-	if (hw_tls && is_rxt) {
+	if (hw_tls && is_rxt && len != 0) {
 		uint64_t rexmit_percent = (1000ULL * tp->t_snd_rxt_bytes) / (10ULL * (tp->t_snd_rxt_bytes + tp->t_sndbytes));
 		if (rexmit_percent > ktls_ifnet_max_rexmit_pct)
 			ktls_disable_ifnet(tp);