CVE-2026-64419 (GCVE-0-2026-64419)

Vulnerability from cvelistv5 – Published: 2026-07-25 08:50 – Updated: 2026-08-17 04:55
VLAI
Title
mm/shrinker: do not hold RCU lock in shrinker_debugfs_count_show()
Summary
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().
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6653 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < de5f69b8dae8698ac5e48dfcd30017887cdf4e5a (git)
Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < e441cbfbd0eaa6404278e985033c33caba4db767 (git)
Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < 2fed79f0fe8c8d28a972c290dbfd693c3546c8c4 (git)
Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < 560e21e8ccff813e84d05f6500907c549a3d6985 (git)
Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < 86237e56091e70f09c0fbf217f9d9c0e08f556c4 (git)
Affected: 5035ebc644aec92d55d1bbfe042f35341e4bffb5 , < b902890c62d200b3509cb5e09cf1e0a66553c128 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.96 , ≤ 6.12.* (semver)
Unaffected: 6.18.39 , ≤ 6.18.* (semver)
Unaffected: 7.1.4 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64419.json",
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}



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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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