CVE-2025-38666 — linux / linux_kernel
Use After FreeIn 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
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 2.6.13 | 5.4.297 |
| linux / linux_kernel | 5.5 | 5.10.241 |
| linux / linux_kernel | 5.11 | 5.15.190 |
| linux / linux_kernel | 5.16 | 6.1.148 |
| linux / linux_kernel | 6.2 | 6.6.101 |
| linux / linux_kernel | 6.7 | 6.12.41 |
| linux / linux_kernel | 6.13 | 6.15.9 |
| linux / linux_kernel | 2.6.12 | 2.6.12.x |
| linux / linux_kernel | 2.6.12-rc2 | 2.6.12-rc2.x |
| linux / linux_kernel | 2.6.12-rc3 | 2.6.12-rc3.x |
| linux / linux_kernel | 2.6.12-rc4 | 2.6.12-rc4.x |
| linux / linux_kernel | 2.6.12-rc5 | 2.6.12-rc5.x |
| linux / linux_kernel | 6.16-rc1 | 6.16-rc1.x |
| linux / linux_kernel | 6.16-rc2 | 6.16-rc2.x |
| linux / linux_kernel | 6.16-rc3 | 6.16-rc3.x |
| linux / linux_kernel | 6.16-rc4 | 6.16-rc4.x |
| linux / linux_kernel | 6.16-rc5 | 6.16-rc5.x |
| linux / linux_kernel | 6.16-rc6 | 6.16-rc6.x |
| linux / linux_kernel | 6.16-rc7 | 6.16-rc7.x |
| debian / debian_linux | 11.0 | 11.0.x |
- https://git.kernel.org/stable/c/186942d19c0222617ef61f50e1dba91e269a5963
- https://git.kernel.org/stable/c/2a6209e4649d45fd85d4193abc481911858ffc6f
- https://git.kernel.org/stable/c/5f02ea0f63dd38c41539ea290fcc1693c73aa8e5
- https://git.kernel.org/stable/c/6c4a92d07b0850342d3becf2e608f805e972467c
- https://git.kernel.org/stable/c/82d19a70ced28b17a38ebf1b6978c6c7db894979
- https://git.kernel.org/stable/c/b35694ffabb2af308a1f725d70f60fd8a47d1f3e
- https://git.kernel.org/stable/c/e4f1564c5b699eb89b3040688fd6b4e57922f1f6
- https://git.kernel.org/stable/c/f90b6bb203f3f38bf2b3d976113d51571df9a482
- https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html
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