APPLIED: [SRU][N/P][PATCH 0/1] CVE-2025-38500

[Stefan Bader]

On 20/08/2025 03:02, Tim Whisonant wrote:
> SRU Justification:
> 
> [Impact]
> 
> 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>
> 
> [Fix]
> 
> Plucky:   applied Noble patch
> Noble:    cherry picked from upstream
> Jammy:    not affected
> Focal:    not affected
> Bionic:   not affected
> Xenial:   not affected
> Trusty:   not affected
> 
> [Test Plan]
> 
> Compile and boot tested.
> 
> [Where problems could occur]
> 
> The changes occur in the transformations IP framework. Issues might
> manifest as memory leaks in the core networking code.
> 
> Eyal Birger (1):
>    xfrm: interface: fix use-after-free after changing collect_md xfrm
>      interface
> 
>   net/xfrm/xfrm_interface_core.c | 7 +------
>   1 file changed, 1 insertion(+), 6 deletions(-)
> 


Applied to plucky,noble:linux/master-next. Thanks.

-Stefan

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