{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2021-47454","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-05-21T14:58:30.833Z","datePublished":"2024-05-22T06:19:44.040Z","dateUpdated":"2025-05-04T12:41:30.543Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2025-05-04T12:41:30.543Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/smp: do not decrement idle task preempt count in CPU offline\n\nWith PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we\nget:\n\nBUG: scheduling while atomic: swapper/1/0/0x00000000\nno locks held by swapper/1/0.\nCPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100\nCall Trace:\n dump_stack_lvl+0xac/0x108\n __schedule_bug+0xac/0xe0\n __schedule+0xcf8/0x10d0\n schedule_idle+0x3c/0x70\n do_idle+0x2d8/0x4a0\n cpu_startup_entry+0x38/0x40\n start_secondary+0x2ec/0x3a0\n start_secondary_prolog+0x10/0x14\n\nThis is because powerpc's arch_cpu_idle_dead() decrements the idle task's\npreempt count, for reasons explained in commit a7c2bb8279d2 (\"powerpc:\nRe-enable preemption before cpu_die()\"), specifically \"start_secondary()\nexpects a preempt_count() of 0.\"\n\nHowever, since commit 2c669ef6979c (\"powerpc/preempt: Don't touch the idle\ntask's preempt_count during hotplug\") and commit f1a0a376ca0c (\"sched/core:\nInitialize the idle task with preemption disabled\"), that justification no\nlonger holds.\n\nThe idle task isn't supposed to re-enable preemption, so remove the\nvestigial preempt_enable() from the CPU offline path.\n\nTested with pseries and powernv in qemu, and pseries on PowerVM."}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/powerpc/kernel/smp.c"],"versions":[{"version":"bdf4d33e8342b90386156204e1da0cdfdb4bf146","lessThan":"53770a411559cf7bc0906d1df319cc533d2f4f58","status":"affected","versionType":"git"},{"version":"2c669ef6979c370f98d4b876e54f19613c81e075","lessThan":"3ea0b497a7a2fff6a4b7090310c9f52c91975934","status":"affected","versionType":"git"},{"version":"2c669ef6979c370f98d4b876e54f19613c81e075","lessThan":"787252a10d9422f3058df9a4821f389e5326c440","status":"affected","versionType":"git"},{"version":"2b6148ef2bd6d8ddc76e7873114f7769b6aa25f0","status":"affected","versionType":"git"},{"version":"20a015e948b825afb47855de2efce7cae7c2608f","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/powerpc/kernel/smp.c"],"versions":[{"version":"5.14","status":"affected"},{"version":"0","lessThan":"5.14","status":"unaffected","versionType":"semver"},{"version":"5.10.76","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.14.15","lessThanOrEqual":"5.14.*","status":"unaffected","versionType":"semver"},{"version":"5.15","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.50","versionEndExcluding":"5.10.76"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"5.14.15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.14","versionEndExcluding":"5.15"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.13.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/53770a411559cf7bc0906d1df319cc533d2f4f58"},{"url":"https://git.kernel.org/stable/c/3ea0b497a7a2fff6a4b7090310c9f52c91975934"},{"url":"https://git.kernel.org/stable/c/787252a10d9422f3058df9a4821f389e5326c440"}],"title":"powerpc/smp: do not decrement idle task preempt count in CPU offline","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2021-47454","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-05-22T19:49:10.356521Z"}}}],"providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-06-04T17:13:30.604Z"}},{"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-08-04T05:39:59.627Z"},"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/53770a411559cf7bc0906d1df319cc533d2f4f58","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/3ea0b497a7a2fff6a4b7090310c9f52c91975934","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/787252a10d9422f3058df9a4821f389e5326c440","tags":["x_transferred"]}]}]}}