{"id":"CVE-2026-31734","state":"PUBLISHED","title":"sched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU\n\nSince commit 8e4f0b1ebcf2 (\"bpf: use rcu_read_lock_dont_migrate() for\ntrampoline.c\"), the BPF prolog (__bpf_prog_enter) calls migrate_disable()\nonly when CONFIG_PREEMPT_RCU is enabled, via rcu_read_lock_dont_migrate().\nWithout CONFIG_PREEMPT_RCU, the prolog never touches migration_disabled,\nso migration_disabled == 1 always means the task is truly\nmigration-disabled regardless of whether it is the current task.\n\nThe old unconditional p == current check was a false negative in this\ncase, potentially allowing a migration-disabled task to be dispatched to\na remote CPU and triggering scx_error in task_can_run_on_remote_rq().\n\nOnly apply the p == current disambiguation when CONFIG_PREEMPT_RCU is\nenabled, where the ambiguity with the BPF prolog still exists.","publishedAt":"2026-05-01T14:14:32.217Z","updatedAt":"2026-05-11T22:14:43.725Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8e4f0b1ebcf2180ab594f204f01279a666dadf3b","status":"affected","lessThan":"72c43eb2e334febe93018cfb68ae828f55c6e49e","versionType":"git"},{"version":"8e4f0b1ebcf2180ab594f204f01279a666dadf3b","status":"affected","lessThan":"b4992a9446bb9a639007bfd32bf5c5a7e30199e5","versionType":"git"},{"version":"8e4f0b1ebcf2180ab594f204f01279a666dadf3b","status":"affected","lessThan":"0c4a59df370bea245695c00aaae6ae75747139bd","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext_idle.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","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_idle.c"]}],"references":["https://git.kernel.org/stable/c/72c43eb2e334febe93018cfb68ae828f55c6e49e","https://git.kernel.org/stable/c/b4992a9446bb9a639007bfd32bf5c5a7e30199e5","https://git.kernel.org/stable/c/0c4a59df370bea245695c00aaae6ae75747139bd"],"weaknesses":[],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/31xxx/CVE-2026-31734.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31734","state":"PUBLISHED","datePublished":"2026-05-01T14:14:32.217Z","dateUpdated":"2026-05-11T22:14:43.725Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-03-09T15:48:24.137Z"},"containers":{"cna":{"title":"sched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix is_bpf_migration_disabled() false negative on non-PREEMPT_RCU\n\nSince commit 8e4f0b1ebcf2 (\"bpf: use rcu_read_lock_dont_migrate() for\ntrampoline.c\"), the BPF prolog (__bpf_prog_enter) calls migrate_disable()\nonly when CONFIG_PREEMPT_RCU is enabled, via rcu_read_lock_dont_migrate().\nWithout CONFIG_PREEMPT_RCU, the prolog never touches migration_disabled,\nso migration_disabled == 1 always means the task is truly\nmigration-disabled regardless of whether it is the current task.\n\nThe old unconditional p == current check was a false negative in this\ncase, potentially allowing a migration-disabled task to be dispatched to\na remote CPU and triggering scx_error in task_can_run_on_remote_rq().\n\nOnly apply the p == current disambiguation when CONFIG_PREEMPT_RCU is\nenabled, where the ambiguity with the BPF prolog still exists."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"8e4f0b1ebcf2180ab594f204f01279a666dadf3b","status":"affected","lessThan":"72c43eb2e334febe93018cfb68ae828f55c6e49e","versionType":"git"},{"version":"8e4f0b1ebcf2180ab594f204f01279a666dadf3b","status":"affected","lessThan":"b4992a9446bb9a639007bfd32bf5c5a7e30199e5","versionType":"git"},{"version":"8e4f0b1ebcf2180ab594f204f01279a666dadf3b","status":"affected","lessThan":"0c4a59df370bea245695c00aaae6ae75747139bd","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["kernel/sched/ext_idle.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.22","status":"unaffected","lessThanOrEqual":"6.18.*","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_idle.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/72c43eb2e334febe93018cfb68ae828f55c6e49e"},{"url":"https://git.kernel.org/stable/c/b4992a9446bb9a639007bfd32bf5c5a7e30199e5"},{"url":"https://git.kernel.org/stable/c/0c4a59df370bea245695c00aaae6ae75747139bd"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T22:14:43.725Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"6.18.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"6.19.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}