CVE-2026-97971

Status: UPDATED  |  Advisory ID: CVE-2026-97971

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

nstree: check listing permission before taking a namespace reference

legitimize_ns() takes a reference on the candidate namespace before

may_list_ns() has decided whether the caller may see it. The

__free(ns_put) cleanup on the denied path can drop the last reference to a

mount namespace while we still hold the rcu read lock, and put_mnt_ns()

may sleep there. This is the same problem commit 2ec2aff3c8e2 ("ns: make

sure reference are dropped outside of rcu lock") fixed for the put_user()

path. Neither ns_requested() nor may_list_ns() needs a reference, both

only look at the namespace type and at the caller's own namespaces, so do

the checks first and take the reference last.

Splat:

Voluntary context switch within RCU read-side critical section!

WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0x238/0x2a0, CPU#5: a/3442

CPU: 5 UID: 1000 PID: 3442 Comm: a Not tainted 7.0.0-30-generic #30-Ubuntu PREEMPT(lazy)

RIP: 0010:rcu_note_context_switch+0x238/0x2a0

Call Trace:

<TASK>

__schedule+0xcf/0x650

schedule+0x27/0x90

schedule_preempt_disabled+0x15/0x30

__mutex_lock.constprop.0+0x550/0xaf0

__mutex_lock_slowpath+0x13/0x20

mutex_lock+0x3b/0x50

exp_funnel_lock+0xb2/0x260

synchronize_rcu_expedited+0xe7/0x220

namespace_unlock+0x26a/0x320

put_mnt_ns+0xd3/0x120

mntns_put+0xe/0x20

do_listns+0x13e/0x560

__do_sys_listns+0x126/0x2d0

__x64_sys_listns+0x20/0x30

x64_sys_call+0x2366/0x2390

do_syscall_64+0x105/0x5a0

entry_SYSCALL_64_after_hwframe+0x76/0x7e

</TASK> (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References