In the Linux kernel, the following vulnerability has been resolved:
netpoll: fix a use-after-free on shutdown path
There is a use-after-free error on netpoll, which is clearly detected by
KASAN.
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80
Read of size 1 at addr ... by task kworker/9:1
Workqueue: events queue_process
Call Trace:
skb_dequeue+0x1e/0xb0
queue_process+0x2c/0x600
process_scheduled_works+0x4b6/0x850
worker_thread+0x414/0x5a0
Allocated by task 242:
__netpoll_setup+0x201/0x4a0
netpoll_setup+0x249/0x550
enabled_store+0x32f/0x380
Freed by task 0:
kfree+0x1b7/0x540
rcu_core+0x3f8/0x7a0
The problem happens when there is a pending TX worker running in
parallel with the cleanup path.
This is what happens on netpoll shutdown path:
1) __netpoll_cleanup() is called
2) set dev->npinfo to NULL
3) call_rcu() with rcu_cleanup_netpoll_info()
3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with
cancel_delayed_work(), but doesn't wait for the worker to finish
4) and kfree(npinfo);
Because 3.1) doesn't really cancel the work, as the comment says "we
can't call cancel_delayed_work_sync here, as we are in softirq", the TX
worker can run after 4).
Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through
the work item via container_of().
Use disable_delayed_work_sync() to ensure the worker is completely
stopped and prevent any future re-arming attempts. Once npinfo is set
to NULL, senders will bail out and not queue new work. The disable flag
ensures any in-flight re-arming attempts also fail silently.
In the future, we can do the cleanup inline here without needing the
npinfo->rcu rcu_head, but that is net-next material.
netpoll: fix a use-after-free on shutdown path
There is a use-after-free error on netpoll, which is clearly detected by
KASAN.
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80
Read of size 1 at addr ... by task kworker/9:1
Workqueue: events queue_process
Call Trace:
skb_dequeue+0x1e/0xb0
queue_process+0x2c/0x600
process_scheduled_works+0x4b6/0x850
worker_thread+0x414/0x5a0
Allocated by task 242:
__netpoll_setup+0x201/0x4a0
netpoll_setup+0x249/0x550
enabled_store+0x32f/0x380
Freed by task 0:
kfree+0x1b7/0x540
rcu_core+0x3f8/0x7a0
The problem happens when there is a pending TX worker running in
parallel with the cleanup path.
This is what happens on netpoll shutdown path:
1) __netpoll_cleanup() is called
2) set dev->npinfo to NULL
3) call_rcu() with rcu_cleanup_netpoll_info()
3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with
cancel_delayed_work(), but doesn't wait for the worker to finish
4) and kfree(npinfo);
Because 3.1) doesn't really cancel the work, as the comment says "we
can't call cancel_delayed_work_sync here, as we are in softirq", the TX
worker can run after 4).
Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through
the work item via container_of().
Use disable_delayed_work_sync() to ensure the worker is completely
stopped and prevent any future re-arming attempts. Once npinfo is set
to NULL, senders will bail out and not queue new work. The disable flag
ensures any in-flight re-arming attempts also fail silently.
In the future, we can do the cleanup inline here without needing the
npinfo->rcu rcu_head, but that is net-next material.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
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No data.
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Linux
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Linux Kernel
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Advisories
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Fixes
Solution
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Workaround
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References
History
Sat, 25 Jul 2026 09:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: netpoll: fix a use-after-free on shutdown path There is a use-after-free error on netpoll, which is clearly detected by KASAN. BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80 Read of size 1 at addr ... by task kworker/9:1 Workqueue: events queue_process Call Trace: skb_dequeue+0x1e/0xb0 queue_process+0x2c/0x600 process_scheduled_works+0x4b6/0x850 worker_thread+0x414/0x5a0 Allocated by task 242: __netpoll_setup+0x201/0x4a0 netpoll_setup+0x249/0x550 enabled_store+0x32f/0x380 Freed by task 0: kfree+0x1b7/0x540 rcu_core+0x3f8/0x7a0 The problem happens when there is a pending TX worker running in parallel with the cleanup path. This is what happens on netpoll shutdown path: 1) __netpoll_cleanup() is called 2) set dev->npinfo to NULL 3) call_rcu() with rcu_cleanup_netpoll_info() 3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with cancel_delayed_work(), but doesn't wait for the worker to finish 4) and kfree(npinfo); Because 3.1) doesn't really cancel the work, as the comment says "we can't call cancel_delayed_work_sync here, as we are in softirq", the TX worker can run after 4). Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through the work item via container_of(). Use disable_delayed_work_sync() to ensure the worker is completely stopped and prevent any future re-arming attempts. Once npinfo is set to NULL, senders will bail out and not queue new work. The disable flag ensures any in-flight re-arming attempts also fail silently. In the future, we can do the cleanup inline here without needing the npinfo->rcu rcu_head, but that is net-next material. | |
| Title | netpoll: fix a use-after-free on shutdown path | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-07-25T08:51:02.276Z
Reserved: 2026-07-19T15:36:31.787Z
Link: CVE-2026-64424
Vulnrichment
No data.
NVD
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Redhat
No data.
OpenCVE Enrichment
Updated: 2026-07-25T22:15:03Z
Weaknesses
No weakness.