Linux Kernel veth XDP no_direct Race in NAPI
CVE-2025-68341 Published on December 23, 2025
veth: reduce XDP no_direct return section to fix race
In the Linux kernel, the following vulnerability has been resolved:
veth: reduce XDP no_direct return section to fix race
As explain in commit fa349e396e48 ("veth: Fix race with AF_XDP exposing
old or uninitialized descriptors") for veth there is a chance after
napi_complete_done() that another CPU can manage start another NAPI
instance running veth_pool(). For NAPI this is correctly handled as the
napi_schedule_prep() check will prevent multiple instances from getting
scheduled, but for the remaining code in veth_pool() this can run
concurrent with the newly started NAPI instance.
The problem/race is that xdp_clear_return_frame_no_direct() isn't
designed to be nested.
Prior to commit 401cb7dae813 ("net: Reference bpf_redirect_info via
task_struct on PREEMPT_RT.") the temporary BPF net context
bpf_redirect_info was stored per CPU, where this wasn't an issue. Since
this commit the BPF context is stored in 'current' task_struct. When
running veth in threaded-NAPI mode, then the kthread becomes the storage
area. Now a race exists between two concurrent veth_pool() function calls
one exiting NAPI and one running new NAPI, both using the same BPF net
context.
Race is when another CPU gets within the xdp_set_return_frame_no_direct()
section before exiting veth_pool() calls the clear-function
xdp_clear_return_frame_no_direct().
Products Associated with CVE-2025-68341
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Affected Versions
Linux:- Version 401cb7dae8130fd34eb84648e02ab4c506df7d5e and below c1ceabcb347d1b0f7e70a7384ec7eff3847b7628 is affected.
- Version 401cb7dae8130fd34eb84648e02ab4c506df7d5e and below d0bd018ad72a8a598ae709588934135017f8af52 is affected.
- Version 401cb7dae8130fd34eb84648e02ab4c506df7d5e and below a14602fcae17a3f1cb8a8521bedf31728f9e7e39 is affected.
- Version 6.11 is affected.
- Before 6.11 is unaffected.
- Version 6.12.61, <= 6.12.* is unaffected.
- Version 6.17.11, <= 6.17.* is unaffected.
- Version 6.18, <= * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.