{"id":"CVE-2026-43326","state":"PUBLISHED","title":"sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback\n\nSCX_KICK_WAIT busy-waits in kick_cpus_irq_workfn() using\nsmp_cond_load_acquire() until the target CPU's kick_sync advances. Because\nthe irq_work runs in hardirq context, the waiting CPU cannot reschedule and\nits own kick_sync never advances. If multiple CPUs form a wait cycle, all\nCPUs deadlock.\n\nReplace the busy-wait in kick_cpus_irq_workfn() with resched_curr() to\nforce the CPU through do_pick_task_scx(), which queues a balance callback\nto perform the wait. The balance callback drops the rq lock and enables\nIRQs following the sched_core_balance() pattern, so the CPU can process\nIPIs while waiting. The local CPU's kick_sync is advanced on entry to\ndo_pick_task_scx() and continuously during the wait, ensuring any CPU that\nstarts waiting for us sees the advancement and cannot form cyclic\ndependencies.","publishedAt":"2026-05-08T13:31:10.184Z","updatedAt":"2026-05-11T22:22:24.156Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"90e55164dad42c6546b698c031697b224a320834","status":"affected","lessThan":"c3a7903f65cf4c7fb0477eb0f8b94f326a47fe54","versionType":"git"},{"version":"90e55164dad42c6546b698c031697b224a320834","status":"affected","lessThan":"415cb193bb9736f0e830286c72a6fa8eb2a9cc5c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext.c","kernel/sched/sched.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext.c","kernel/sched/sched.h"]}],"references":["https://git.kernel.org/stable/c/c3a7903f65cf4c7fb0477eb0f8b94f326a47fe54","https://git.kernel.org/stable/c/415cb193bb9736f0e830286c72a6fa8eb2a9cc5c"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:57.932Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43326.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43326","state":"PUBLISHED","datePublished":"2026-05-08T13:31:10.184Z","dateUpdated":"2026-05-11T22:22:24.156Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:56.002Z"},"containers":{"cna":{"title":"sched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix SCX_KICK_WAIT deadlock by deferring wait to balance callback\n\nSCX_KICK_WAIT busy-waits in kick_cpus_irq_workfn() using\nsmp_cond_load_acquire() until the target CPU's kick_sync advances. Because\nthe irq_work runs in hardirq context, the waiting CPU cannot reschedule and\nits own kick_sync never advances. If multiple CPUs form a wait cycle, all\nCPUs deadlock.\n\nReplace the busy-wait in kick_cpus_irq_workfn() with resched_curr() to\nforce the CPU through do_pick_task_scx(), which queues a balance callback\nto perform the wait. The balance callback drops the rq lock and enables\nIRQs following the sched_core_balance() pattern, so the CPU can process\nIPIs while waiting. The local CPU's kick_sync is advanced on entry to\ndo_pick_task_scx() and continuously during the wait, ensuring any CPU that\nstarts waiting for us sees the advancement and cannot form cyclic\ndependencies."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"90e55164dad42c6546b698c031697b224a320834","status":"affected","lessThan":"c3a7903f65cf4c7fb0477eb0f8b94f326a47fe54","versionType":"git"},{"version":"90e55164dad42c6546b698c031697b224a320834","status":"affected","lessThan":"415cb193bb9736f0e830286c72a6fa8eb2a9cc5c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext.c","kernel/sched/sched.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.12","versionType":"semver"},{"version":"6.19.12","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext.c","kernel/sched/sched.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/c3a7903f65cf4c7fb0477eb0f8b94f326a47fe54"},{"url":"https://git.kernel.org/stable/c/415cb193bb9736f0e830286c72a6fa8eb2a9cc5c"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:22:24.156Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.19.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}