mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()
Summary
| CVE | CVE-2026-64419 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-25 10:17:25 UTC |
| Updated | 2026-07-25 10:17:25 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show() Reading the debugfs "count" file of a memcg-aware shrinker can sleep inside an RCU read-side critical section: BUG: sleeping function called from invalid context at kernel/cgroup/rstat.c:421 RCU nest depth: 1, expected: 0 css_rstat_flush mem_cgroup_flush_stats zswap_shrinker_count shrinker_debugfs_count_show shrinker_debugfs_count_show() invokes the ->count_objects() callback under rcu_read_lock(). The zswap callback flushes memcg stats via css_rstat_flush(), which may sleep, so it must not run under RCU. The RCU lock is not needed here. mem_cgroup_iter() takes RCU internally and returns a memcg holding a css reference (dropped on the next iteration or by mem_cgroup_iter_break()), so the memcg stays alive without it. The shrinker is kept alive by the open debugfs file: shrinker_free() removes the debugfs entries via debugfs_remove_recursive(), which waits for in-flight readers to drain, before call_rcu(..., shrinker_free_rcu_cb). The sibling "scan" handler already invokes the sleeping ->scan_objects() callback with no RCU section. Drop the rcu_read_lock()/rcu_read_unlock(). |
Risk And Classification
EPSS: 0.001730000 probability, percentile 0.069630000 (date 2026-07-28)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 de5f69b8dae8698ac5e48dfcd30017887cdf4e5a git | Not specified |
| CNA | Linux | Linux | affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 e441cbfbd0eaa6404278e985033c33caba4db767 git | Not specified |
| CNA | Linux | Linux | affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 git | Not specified |
| CNA | Linux | Linux | affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 560e21e8ccff813e84d05f6500907c549a3d6985 git | Not specified |
| CNA | Linux | Linux | affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 86237e56091e70f09c0fbf217f9d9c0e08f556c4 git | Not specified |
| CNA | Linux | Linux | affected 5035ebc644aec92d55d1bbfe042f35341e4bffb5 b902890c62d200b3509cb5e09cf1e0a66553c128 git | Not specified |
| CNA | Linux | Linux | affected 6.0 | Not specified |
| CNA | Linux | Linux | unaffected 6.0 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.178 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.145 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.96 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.39 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.4 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/86237e56091e70f09c0fbf217f9d9c0e08f556c4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e441cbfbd0eaa6404278e985033c33caba4db767 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/de5f69b8dae8698ac5e48dfcd30017887cdf4e5a | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/b902890c62d200b3509cb5e09cf1e0a66553c128 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/560e21e8ccff813e84d05f6500907c549a3d6985 | 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.