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charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Proofpoint-ORIG-GUID: 68CluRHbLi6pYgDnDTBbDG2EaSo8rmdi X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDE3MDA4NyBTYWx0ZWRfX4lhsGI78Jt9n eDyekk7LVpJdWEZS2nIppRx5lA4sbdGWfzM/oChqFYOYguyqJ7C+JcsUJ1URFyknolRQcHz+3O0 4Xm7M3gGMtEy7wAp/vUG9S8N+rpL5dxEfKpZ2d2kfBWyrT/5yx+UvaQh14WvWWOf0erTkIOrJ0m wxo7tcCPGaAxWU6S+GKJGtrO9zQ1vQ/O60S0dYhbmu1VUbY4DmZfzAGUG63KhMIcu7wYYJ6TNeG CBI7xKZDc2WGoIC8hbBlAC2X55nTeCraa0s7FLoDETHNTxZ37Na2lbk6sVAAp9WjKKc0fWkvVEg 9/bz44QJlzf9hECtlh6vCKN1+vMM0RvKQNEug3Rjfgw1NuVXA2Sg8ap3x15P8/AbY5MOi4yhUOy oGny419HHzVpHT6eTH5YqmzxOSoPsv1WTqbfylWH2H6D0Kfm0iRt6L2D9Dk9Rh3q0+5s4RymA3T /lHTwN6UntgF464VBEQ== X-Proofpoint-Spam-Info: AW1haW4tMjYxMDE3MDA4NyBTYWx0ZWRfXx7gG/OlX2kfb Y+YQ6BmslBqrSs5ncaLk+5i/Hu1pWNSHfpWpDqydGxq0Xy76SRfjJc7ua4pd3CvTn9efDugH9Gs nclULkpSfzMZs8D44gnp65jd8n/TViw= X-Proofpoint-GUID: 68CluRHbLi6pYgDnDTBbDG2EaSo8rmdi X-Authority-Analysis: v=2.4 cv=RMomjIi+ c=1 sm=1 tr=0 ts=6ad3ee0a cx=c_pps a=Uww141gWH0fZj/3QKPojxA==:117 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=x7bEGLp0ZPQA:10 a=S0S_EcBMpFAA:10 a=VkNPw1HP01LnGYTKEx00:22 a=Se5WoFf3ZZRiLcel0nel:22 a=_0uBWF9-lnOxR1nRej8j:22 a=VwQbUJbxAAAA:8 a=1XWaLZrsAAAA:8 a=LDwnR17CkXKMPNxMdHAA:9 a=QEXdDO2ut3YA:10 a=PxkB5W3o20Ba91AHUih5:22 X-Orig-IP: 74.125.82.197 X-Proofpoint-Spam-Details: rule=outbound_bp_notspam policy=outbound_bp score=0 suspectscore=0 adultscore=0 malwarescore=0 spamscore=0 clxscore=1015 priorityscore=1501 phishscore=0 lowpriorityscore=0 impostorscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610170087 I've made some further changes using suggestions on my v2 patch and using !val. This change should prevent all future errors regarding snd_cwnd and snd_cwnd_clamp being 0. v4 has been proposed: https://lore.kernel.org/all/20261017214845.28769-2-kj2864@nyu.edu/ On Sat, Oct 17, 2026 at 1:21=E2=80=AFAM wrote: > > On Thu, 15 Oct 2026 16:15:50 -0400, Kaho Jiang wrote: > > User can pass zero to snd_cwnd_clamp via RTAX_CWND type. > > This could lead to division of zero error if not checked properly. > > > > Oops: divide error: 0000 [#1] SMP KASAN NOPTI > > Call Trace: > > > > tcp_reno_cong_avoid (net/ipv4/tcp_cong.c:510 (discriminator 1)) > > tcp_ack (net/ipv4/tcp_input.c:3517 net/ipv4/tcp_input.c:3873 net/ipv4/= tcp_input.c:4440) > > tcp_rcv_established (net/ipv4/tcp_input.c:6685) > > tcp_v4_do_rcv (net/ipv4/tcp_ipv4.c:1854) > > tcp_v4_rcv (net/ipv4/tcp_ipv4.c:2248) > > ip_protocol_deliver_rcu (net/ipv4/ip_input.c:207 (discriminator 1)) > > ip_local_deliver_finish (net/ipv4/ip_input.c:241 (discriminator 1)) > > ip_local_deliver (./include/linux/netfilter.h:325 ./include/linux/netf= ilter.h:319 net/ipv4/ip_input.c:262) > > ip_rcv (./include/net/dst.h:481 (discriminator 6) net/ipv4/ip_input.c:= 492 (discriminator 6) ./include/linux/netfilter.h:325 (discriminator 6) ./i= nclude/li) > > __netif_receive_skb_one_core (net/core/dev.c:6297 (discriminator 4)) > > __netif_receive_skb (net/core/dev.c:6410) > > process_backlog (net/core/dev.c:6761) > > __napi_poll.constprop.0 (net/core/dev.c:7830) > > net_rx_action (net/core/dev.c:7893 net/core/dev.c:8050) > > handle_softirqs (kernel/softirq.c:645) > > __irq_exit_rcu (kernel/softirq.c:679 kernel/softirq.c:519 kernel/softi= rq.c:758) > > irq_exit_rcu (kernel/softirq.c:775) > > sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1062 (discrim= inator 35) arch/x86/kernel/apic/apic.c:1062 (discriminator 35)) > > RIP: 0010:tcp_cong_avoid_ai (net/ipv4/tcp_cong.c:482) > > > > Fix by checking if user pass in zero as parameter, > > if so reject the value zero. > > > > Fixes: 814d488c6126 ("tcp: fix the timid additive increase on stretch A= CKs") > > Cc: stable@vger.kernel.org > > Reported-by: co+71b6509cb791e531@bugs.sh > > Assisted-by: LLM > > Signed-off-by: Kaho Jiang > > --- > > net/ipv4/metrics.c | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/net/ipv4/metrics.c b/net/ipv4/metrics.c > > index ad40762a8b38..e83a129a25b6 100644 > > --- a/net/ipv4/metrics.c > > +++ b/net/ipv4/metrics.c > > @@ -54,6 +54,10 @@ static int ip_metrics_convert(struct nlattr *fc_mx, > > NL_SET_ERR_MSG(extack, "Unknown flag set in featu= re mask in metrics attribute"); > > return -EINVAL; > > } > > + if (type =3D=3D RTAX_CWND && val =3D=3D 0) { > > While at it, please check RTAX_INITCWND too (although it is > ignored and TCP_INIT_CWND is used), also use !val. > > > > + NL_SET_ERR_MSG(extack, "RTAX_CWND must be greater= than zero"); > > + return -EINVAL; > > + } > > metrics[type - 1] =3D val; > > } > > > > -- > > 2.43.0 > >