CVE-2026-74479

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.