net: udp_tunnel: fix memory leak in udp_tunnel_nic_unregister()
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/
CVE-2026-74543
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-74543
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
"lessThan": "52c753b46265243406690d980faa9514d3f53827",
"versionType": "git"
},
{
"status": "affected",
"version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
"lessThan": "b712da45bd9b9835d132e9fbc0c3e43c164cb1fd",
"versionType": "git"
},
{
"status": "affected",
"version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
"lessThan": "f82a2ded3d7a9098267c84f14eafdb98c4550ac5",
"versionType": "git"
},
{
"status": "affected",
"version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
"lessThan": "b322532a4b774db1b480a2de84125910a70739a5",
"versionType": "git"
},
{
"status": "affected",
"version": "cc4e3835eff474aa274d6e1d18f69d9d296d3b76",
"lessThan": "080695e6f005e2396f1207fd69d24c442cb230c6",
"versionType": "git"
}
],
"programFiles": [
"net/ipv4/udp_tunnel_nic.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "5.9"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "5.9",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.160",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.103",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.44",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.8",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv4/udp_tunnel_nic.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-74543
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #46573 · Revision 1
- Added to Heist Feed
- Publisher date