{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-52946", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-52946", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-06-24T16:26:04.419Z", "updatedAt": "2026-10-19T19:47:09.047Z", "importedAt": "2026-10-24T01:58:14.884Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "fs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/fcntl: fix SOFTIRQ-unsafe lock order in fasync signaling\n\nA SOFTIRQ-safe to SOFTIRQ-unsafe lock order deadlock can occur in\nsend_sigio() and send_sigurg() when a process group receives a signal.\n\nWhen FASYNC is configured for a process group (PIDTYPE_PGID), both\nfunctions use read_lock(&tasklist_lock) to traverse the task list.\nHowever, they are frequently called from softirq context:\n- send_sigio() via input_inject_event -> kill_fasync\n- send_sigurg() via tcp_check_urg -> sk_send_sigurg (NET_RX_SOFTIRQ)\n\nThe deadlock is caused by the rwlock writer fairness mechanism:\n1. CPU 0 (process context) holds read_lock(&tasklist_lock) in do_wait().\n2. CPU 1 (process context) attempts write_lock(&tasklist_lock) in\n fork() or exit() and spins, which blocks all new readers.\n3. CPU 0 is interrupted by a softirq (e.g., TCP URG packet reception).\n4. The softirq calls send_sigurg() and attempts to acquire\n read_lock(&tasklist_lock), deadlocking because CPU 1 is waiting.\n\nSince PID hashing and do_each_pid_task() traversals are already\nRCU-protected, the read_lock on tasklist_lock is no longer strictly\nrequired for safe traversal. Fix this by replacing tasklist_lock with\nrcu_read_lock(), aligning the process group signaling path with the\nsingle-PID path. This also mitigates a potential remote denial of\nservice vector via TCP URG packets.\n\nLockdep splat:\n=====================================================\nWARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected\n[...]\nChain exists of:\n &dev->event_lock --> &f_owner->lock --> tasklist_lock\n\nPossible interrupt unsafe locking scenario:\n CPU0 CPU1\n ---- ----\n lock(tasklist_lock);\n local_irq_disable();\n lock(&dev->event_lock);\n lock(&f_owner->lock);\n \n lock(&dev->event_lock);\n\n*** DEADLOCK ***", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "54626335ea4174ab2d9a183b511d825f6765e47b" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "897d6a7247739fb1528f98c575df4f2e5de7f994" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "32dbd5ce4be3a3ed7e00f8af18795cc84fc50a33" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "b5fa9e32fb6718f70c986ee14dd5d01b4846f331" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "1bee417678f1135e35b25a37734db46aa94258d2" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "20a93e397abe850c49b6fa0e8cc827b5f634a8f5" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "bfcc8e8d8a495bb34cae9e620adfb75fb13a3954" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "36c1b57b2ecf3c61ac93f5f07bd29b6f21e226ed" }, { "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "status": "affected", "versionType": "git", "lessThan": "00633c4683828acd5256fa8d5163f440d74bbe71" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.12", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.12" }, { "version": "5.10.259", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.210", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.176", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.143", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.94", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.36", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.0.13", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1.1", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }