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/netfilter.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) ./include/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/softirq.c:758) irq_exit_rcu (kernel/softirq.c:775) sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1062 (discriminator 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 ACKs") Cc: stable@vger.kernel.org Reported-by: co+71b6509cb791e531@bugs.sh Assisted-by: LLM Signed-off-by: Kaho Jiang --- include/net/tcp.h | 3 +-- net/ipv4/metrics.c | 4 ++++ 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 4416cdf9bf30..ad80b8fb8a52 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1521,8 +1521,7 @@ static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp) static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val) { - WARN_ON_ONCE((int)val <= 0); - WRITE_ONCE(tp->snd_cwnd, val); + WRITE_ONCE(tp->snd_cwnd, max(val, 1U)); } static inline bool tcp_in_slow_start(const struct tcp_sock *tp) diff --git a/net/ipv4/metrics.c b/net/ipv4/metrics.c index ad40762a8b38..cb36686973e5 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 feature mask in metrics attribute"); return -EINVAL; } + if (type == RTAX_CWND && !val) { + NL_SET_ERR_MSG(extack, "RTAX_CWND must be greater than zero"); + return -EINVAL; + } metrics[type - 1] = val; } -- 2.43.0