CVE-2026-74479net: pktgen: fix proc entry use-after-free

Official description

In the Linux kernel, the following vulnerability has been resolved: net: pktgen: fix proc entry use-after-free pktgen_change_name() replaces pkt_dev->entry while holding t->if_lock. pktgen_remove_device() removes the same entry before _rem_dev_from_if_list() takes that lock. This allows the following interleaving: CPU 0 (NETDEV_CHANGENAME) CPU 1 (kpktgend) if_lock(t) proc_remove(pkt_dev->entry) proc_remove(pkt_dev->entry) pkt_dev->entry = proc_create_data(...) if_unlock(t) The kthread can pass the stale proc_dir_entry to proc_remove() after the rename path has freed it. A reproducer with a widened race window reports: BUG: KASAN: slab-use-after-free in proc_remove+0x78/0x80 Read of size 8 at addr ffff8881478fea70 by task kpktgend_0/67 Call Trace: proc_remove+0x78/0x80 pktgen_remove_device.isra.0+0x11c/0x4c0 pktgen_thread_worker+0x1214/0x6bc0 kthread+0x2c6/0x3b0 Allocated by task 95: __proc_create+0x204/0x790 proc_create_data+0x72/0xe0 pktgen_thread_write+0xd61/0x1510 Freed by task 28: kmem_cache_free+0xcb/0x3d0 proc_free_inode+0x5b/0x80 rcu_core+0x50a/0x1850 The buggy address belongs to the object at ffff8881478fea00 which belongs to the cache proc_dir_entry of size 192 Move proc_remove() into the if_lock-protected list removal helper. Keep it before list_del_rcu() to preserve the ordering required by add_device(). The rename path must then finish replacing the entry before removal, or it observes that the device is no longer on the list.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/82ed3db9269cb61e3c15bad2f6e221efce90e1e0
• https://git.kernel.org/stable/c/d1cc9797cf8f7aeb87e7ad01b748c6a960a819e4
• https://git.kernel.org/stable/c/7991c7cff8b8622cddb3d8dee07dbe74aa4cbec4
• https://git.kernel.org/stable/c/577443530cb592d5782a1f79847411a9363a65c8
• https://git.kernel.org/stable/c/f85a58340b91f225de3299dfa782c6414098077c
• https://git.kernel.org/stable/c/4ef801b838d85c0ea5852c50667f7344ce3b6cd0
• https://git.kernel.org/stable/c/b006a5404470bd3eb2aa0425fc447183032047ef
• https://git.kernel.org/stable/c/817ff6efdb7f484ea547218e11e17d8e43daa3b4