CVE-2025-40064: In the Linux kernel, the following vulnerability has been resolved: smc: Fix use-after-free in __pnet_find_base

In the Linux kernel, the following vulnerability has been resolved: smc: Fix use-after-free in __pnet_find_base_ndev().

In the Linux kernel, the following vulnerability has been resolved: smc: Fix use-after-free in __pnet_find_base_ndev(). syzbot reported use-after-free of net_device in __pnet_find_base_ndev(), which was called during connect(). [0] smc_pnet_find_ism_resource() fetches sk_dst_get(sk)->dev and passes down to pnet_find_base_ndev(), where RTNL is held. Then, UAF happened at __pnet_find_base_ndev() when the dev is first used. This means dev had already been freed before acquiring RTNL in pnet_find_base_ndev(). While dev is going away, dst->dev could be swapped with blackhole_netdev, and the dev's refcnt by dst will be released. We must hold dev's refcnt before calling smc_pnet_find_ism_resource(). Also, smc_pnet_find_roce_resource() has the same problem. Let's use __sk_dst_get() and dst_dev_rcu() in the two functions. [0]: BUG: KASAN: use-after-free in __pnet_find_base_ndev+0x1b1/0x1c0 net/smc/smc_pnet.c:926 Read of size 1 at addr ffff888036bac33a by task syz.0.3632/18609 CPU: 1 UID: 0 PID: 18609 Comm: syz.0.3632 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: <TASK> dump_stack_lvl+

Description from the National Vulnerability Database, published by 416baaa9-dc9f-4396-8d5f-8c081fb06d67

What it means for a small business

Linux is on the computers, phones or browsers your team uses every day. Turn on automatic updates and restart: most of these fixes only take effect after a restart.

How likely is an attack? The Exploit Prediction Scoring System, run by FIRST (the global association of security response teams), puts the odds of this one being exploited in the next 30 days at 0.15%, higher than 4% of CVEs. That’s low, but low isn’t zero, and the odds jump the day someone publishes an exploit. Scored October 29, 2026, updated daily.

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Sources

Part of the Huttenlocher Technologies vulnerability database, refreshed twice a day from CISA and the NVD. The title, category and plain-language guidance are ours; check the linked record before acting on a detail. This is general guidance, not a review of your systems.

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