Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: quota: Fix race of dquot_scan_active() with quota deactivation dquot_scan_active() can race with quota deactivation in quota_release_workfn() like: CPU0 (quota_release_workfn) CPU1 (dquot_scan_active) ============================== ============================== spin_lock(&dq_list_lock); list_replace_init( &releasing_dquots, &rls_head); /* dquot X on rls_head, dq_count == 0, DQ_ACTIVE_B still set */ spin_unlock(&dq_list_lock); synchronize_srcu(&dquot_srcu); spin_lock(&dq_list_lock); list_for_each_entry(dquot, &inuse_list, dq_inuse) { /* finds dquot X */ dquot_active(X) -> true atomic_inc(&X->dq_count); } spin_unlock(&dq_list_lock); spin_lock(&dq_list_lock); dquot = list_first_entry(&rls_head); WARN_ON_ONCE(atomic_read(&dquot->dq_count)); The problem is not only a cosmetic one as under memory pressure the caller of dquot_scan_active() can end up working on freed dquot. Fix the problem by making sure the dquot is removed from releasing list when we acquire a reference to it.

Affected versions

Linux: 22c06bf1f99ec3ec16b1a81342becba4c59a1f16 through before 2bdc80f4619411e5bd4a3ef23f51e14021ed457c (git); 56e96b38d2f7cd95b3c30eb70decac7233915e0a through before f9438cb8c8ec3adc84b2b450a3aab0123d074c3b (git); 12a820a9923c11e8e898da9f82c8aded70cdcd16 through before ac8a2e0d287ebf35e5d7e51e260b4e146648ba4a (git); 869b6ea1609f655a43251bf41757aa44e5350a8f through before 6678dde265708003c2b42551af4a2e3cb05decd5 (git); 869b6ea1609f655a43251bf41757aa44e5350a8f through before 61e25f664dc2a08299e07d84c85776abc2350f75 (git); 869b6ea1609f655a43251bf41757aa44e5350a8f through before fdd424d7c35633ac577fd87d1b043d1b8a6cd350 (git); 869b6ea1609f655a43251bf41757aa44e5350a8f through before 82cbdb4c1ebb5ea7d7bd45c18d3483b5bd32ebc1 (git); 869b6ea1609f655a43251bf41757aa44e5350a8f through before e93ab401da4b2e2c1b8ef2424de2f238d51c8b2d (git); bb7e3a019b52d829949d02b64ebab37838148fbf (git); 061a18239ced5eb086967a2b4451cb1cc5ce0702 (git); 2a1ddddba6541143c8f73962f3021f1789114284 (git); 5.10.199 through before 5.10.258 (semver); 5.15.136 through before 5.15.209 (semver); 6.1.59 through before 6.1.175 (semver); 4.19.297 through before 4.20 (semver); 5.4.259 through before 5.5 (semver); 6.5.8 through before 6.6 (semver); 6.6; V3.1.6 through before * (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.