CVE-2025-38666
In the Linux kernel, the following vulnerability has been resolved:
net: appletalk: Fix use-after-free in AARP proxy probe
The AARP proxy‐probe routine (aarp_proxy_probe_network) sends a probe,
releases the aarp_lock, sleeps, then re-acquires the lock. During that
window an expire timer thread (__aarp_expire_timer) can remove and
kfree() the same entry, leading to a use-after-free.
race condition:
cpu 0 | cpu 1
atalk_sendmsg() | atif_proxy_probe_device()
aarp_send_ddp() | aarp_proxy_probe_network()
mod_timer() | lock(aarp_lock) // LOCK!!
timeout around 200ms | alloc(aarp_entry)
and then call | proxies[hash] = aarp_entry
aarp_expire_timeout() | aarp_send_probe()
| unlock(aarp_lock) // UNLOCK!!
lock(aarp_lock) // LOCK!! | msleep(100);
__aarp_expire_timer(&proxies[ct]) |
free(aarp_entry) |
unlock(aarp_lock) // UNLOCK!! |
| lock(aarp_lock) // LOCK!!
| UAF aarp_entry !!
==================================================================
BUG: KASAN: slab-use-after-free in aarp_proxy_probe_network+0x560/0x630 net/appletalk/aarp.c:493
Read of size 4 at addr ffff8880123aa360 by task repro/13278
CPU: 3 UID: 0 PID: 13278 Comm: repro Not tainted 6.15.2 #3 PREEMPT(full)
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xc1/0x630 mm/kasan/report.c:521
kasan_report+0xca/0x100 mm/kasan/report.c:634
aarp_proxy_probe_network+0x560/0x630 net/appletalk/aarp.c:493
atif_proxy_probe_device net/appletalk/ddp.c:332 [inline]
atif_ioctl+0xb58/0x16c0 net/appletalk/ddp.c:857
atalk_ioctl+0x198/0x2f0 net/appletalk/ddp.c:1818
sock_do_ioctl+0xdc/0x260 net/socket.c:1190
sock_ioctl+0x239/0x6a0 net/socket.c:1311
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl fs/ioctl.c:892 [inline]
__x64_sys_ioctl+0x194/0x200 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcb/0x250 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
</TASK>
Allocated:
aarp_alloc net/appletalk/aarp.c:382 [inline]
aarp_proxy_probe_network+0xd8/0x630 net/appletalk/aarp.c:468
atif_proxy_probe_device net/appletalk/ddp.c:332 [inline]
atif_ioctl+0xb58/0x16c0 net/appletalk/ddp.c:857
atalk_ioctl+0x198/0x2f0 net/appletalk/ddp.c:1818
Freed:
kfree+0x148/0x4d0 mm/slub.c:4841
__aarp_expire net/appletalk/aarp.c:90 [inline]
__aarp_expire_timer net/appletalk/aarp.c:261 [inline]
aarp_expire_timeout+0x480/0x6e0 net/appletalk/aarp.c:317
The buggy address belongs to the object at ffff8880123aa300
which belongs to the cache kmalloc-192 of size 192
The buggy address is located 96 bytes inside of
freed 192-byte region [ffff8880123aa300, ffff8880123aa3c0)
Memory state around the buggy address:
ffff8880123aa200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880123aa280: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880123aa300: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880123aa380: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff8880123aa400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
Attack Parameters
Technical Impact
Affected Configurations
Total: 4566 detected entries
Time Line
Key Metrics
Recommended Solution
Immediate Action Plan
1. Inventory
Identify all affected systems in your infrastructure.
2. Assessment
Assess exposure and criticality for your organization.
3. Mitigation
Apply patches or available workarounds.
4. Verification
Test and confirm effectiveness of applied measures.
