CVE-2025-38500: Linux Kernel Fix: Prevents Data Loss on xfrm Interfaces

Summary

A vulnerability in the Linux kernel has been fixed, which could have caused data loss on certain network interfaces. The issue was resolved by adding a check to prevent changes to interfaces with the 'collect_md' property after they are created. This change ensures that such interfaces are not mistakenly added to the kernel's hash table twice, which could lead to data corruption or loss when the network namespace is shut down.

What to do

No fix is available yet. Check with your software vendor for updates.

Affected software

Vendor	Product	Affected versions
linux	linux_kernel	>= 6.1, < 6.1.148 >= 6.2, < 6.6.101 >= 6.7, < 6.12.41 >= 6.13, < 6.15.9 6.16 `cpe:2.3:o:linux:linux_kernel::::::::`
debian	debian_linux	11.0 `cpe:2.3:o:debian:debian_linux:11.0:::::::*`

Original title

In the Linux kernel, the following vulnerability has been resolved: xfrm: interface: fix use-after-free after changing collect_md xfrm interface collect_md property on xfrm interfaces can only be...

Original description

In the Linux kernel, the following vulnerability has been resolved:

xfrm: interface: fix use-after-free after changing collect_md xfrm interface

collect_md property on xfrm interfaces can only be set on device creation,
thus xfrmi_changelink() should fail when called on such interfaces.

The check to enforce this was done only in the case where the xi was
returned from xfrmi_locate() which doesn't look for the collect_md
interface, and thus the validation was never reached.

Calling changelink would thus errornously place the special interface xi
in the xfrmi_net->xfrmi hash, but since it also exists in the
xfrmi_net->collect_md_xfrmi pointer it would lead to a double free when
the net namespace was taken down [1].

Change the check to use the xi from netdev_priv which is available earlier
in the function to prevent changes in xfrm collect_md interfaces.

[1] resulting oops:
[ 8.516540] kernel BUG at net/core/dev.c:12029!
[ 8.516552] Oops: invalid opcode: 0000 [#1] SMP NOPTI
[ 8.516559] CPU: 0 UID: 0 PID: 12 Comm: kworker/u80:0 Not tainted 6.15.0-virtme #5 PREEMPT(voluntary)
[ 8.516565] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 8.516569] Workqueue: netns cleanup_net
[ 8.516579] RIP: 0010:unregister_netdevice_many_notify+0x101/0xab0
[ 8.516590] Code: 90 0f 0b 90 48 8b b0 78 01 00 00 48 8b 90 80 01 00 00 48 89 56 08 48 89 32 4c 89 80 78 01 00 00 48 89 b8 80 01 00 00 eb ac 90 <0f> 0b 48 8b 45 00 4c 8d a0 88 fe ff ff 48 39 c5 74 5c 41 80 bc 24
[ 8.516593] RSP: 0018:ffffa93b8006bd30 EFLAGS: 00010206
[ 8.516598] RAX: ffff98fe4226e000 RBX: ffffa93b8006bd58 RCX: ffffa93b8006bc60
[ 8.516601] RDX: 0000000000000004 RSI: 0000000000000000 RDI: dead000000000122
[ 8.516603] RBP: ffffa93b8006bdd8 R08: dead000000000100 R09: ffff98fe4133c100
[ 8.516605] R10: 0000000000000000 R11: 00000000000003d2 R12: ffffa93b8006be00
[ 8.516608] R13: ffffffff96c1a510 R14: ffffffff96c1a510 R15: ffffa93b8006be00
[ 8.516615] FS: 0000000000000000(0000) GS:ffff98fee73b7000(0000) knlGS:0000000000000000
[ 8.516619] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 8.516622] CR2: 00007fcd2abd0700 CR3: 000000003aa40000 CR4: 0000000000752ef0
[ 8.516625] PKRU: 55555554
[ 8.516627] Call Trace:
[ 8.516632] <TASK>
[ 8.516635] ? rtnl_is_locked+0x15/0x20
[ 8.516641] ? unregister_netdevice_queue+0x29/0xf0
[ 8.516650] ops_undo_list+0x1f2/0x220
[ 8.516659] cleanup_net+0x1ad/0x2e0
[ 8.516664] process_one_work+0x160/0x380
[ 8.516673] worker_thread+0x2aa/0x3c0
[ 8.516679] ? __pfx_worker_thread+0x10/0x10
[ 8.516686] kthread+0xfb/0x200
[ 8.516690] ? __pfx_kthread+0x10/0x10
[ 8.516693] ? __pfx_kthread+0x10/0x10
[ 8.516697] ret_from_fork+0x82/0xf0
[ 8.516705] ? __pfx_kthread+0x10/0x10
[ 8.516709] ret_from_fork_asm+0x1a/0x30
[ 8.516718] </TASK>

nvd CVSS3.1 7.8

Vulnerability type

CWE-416 Use After Free