net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()
Summary
| CVE | CVE-2026-74543 |
|---|
| State | PUBLISHED |
|---|
| Assigner | Linux |
|---|
| Source Priority | CVE Program / NVD first with legacy fallback |
|---|
| Published | 2026-08-15 13:17:59 UTC |
|---|
| Updated | 2026-08-15 13:17:59 UTC |
|---|
| Description | In the Linux kernel, the following vulnerability has been resolved:
net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()
syzbot reported a memory leak [1] in the UDP tunnel NIC offload code.
When device registration fails (e.g. in register_netdevice()), netdev core
unwinds by sending a single NETDEV_UNREGISTER notification. If work was queued
during NETDEV_REGISTER (utn->work_pending is set), udp_tunnel_nic_unregister()
returns early:
if (utn->work_pending)
return;
Because failed registrations do not enter netdev_wait_allrefs_any(), no
subsequent NETDEV_UNREGISTER rebroadcast will ever occur. As a result, the
struct udp_tunnel_nic allocated in udp_tunnel_nic_alloc() is leaked
permanently.
Fix this by removing the early return. Instead, synchronously cancel any
pending work with cancel_delayed_work_sync() before freeing @utn.
To be able to call cancel_delayed_work_sync() while holding RTNL (the work also
needs RTNL), switch udp_tunnel_nic_device_sync_work() to rtnl_trylock(). If RTNL
is contended, requeue the work with a 1 jiffy delay (via queue_delayed_work())
to prevent high CPU contention while waiting for RTNL lock.
The utn->work_pending bookkeeping is no longer needed and is removed, as
the workqueue core already tracks the pending/running state of the work.
[1]
BUG: memory leak
unreferenced object 0xffff888127d5f840 (size 96):
comm "syz-executor", pid 5806, jiffies 4294942188
backtrace (crc 99fdb6c8):
__kmalloc_noprof+0x3bf/0x550
udp_tunnel_nic_alloc net/ipv4/udp_tunnel_nic.c:756 [inline]
udp_tunnel_nic_register net/ipv4/udp_tunnel_nic.c:833 [inline]
udp_tunnel_nic_netdevice_event+0x804/0xab0 net/ipv4/udp_tunnel_nic.c:931
notifier_call_chain+0x59/0x160 kernel/notifier.c:85
call_netdevice_notifiers_info+0x7d/0xb0 net/core/dev.c:2250
register_netdevice+0xc10/0xeb0 net/core/dev.c:11478 |
|---|
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 b712da45bd9b9835d132e9fbc0c3e43c164cb1fd git |
Not specified |
| CNA |
Linux |
Linux |
affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 f82a2ded3d7a9098267c84f14eafdb98c4550ac5 git |
Not specified |
| CNA |
Linux |
Linux |
affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 b322532a4b774db1b480a2de84125910a70739a5 git |
Not specified |
| CNA |
Linux |
Linux |
affected cc4e3835eff474aa274d6e1d18f69d9d296d3b76 080695e6f005e2396f1207fd69d24c442cb230c6 git |
Not specified |
| CNA |
Linux |
Linux |
affected 5.9 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 5.9 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.103 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.44 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.1.8 7.1.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2-rc6 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/080695e6f005e2396f1207fd69d24c442cb230c6 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/b712da45bd9b9835d132e9fbc0c3e43c164cb1fd |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/b322532a4b774db1b480a2de84125910a70739a5 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/f82a2ded3d7a9098267c84f14eafdb98c4550ac5 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.