{"id":"CVE-2021-47217","state":"PUBLISHED","title":"x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails\n\nCheck for a valid hv_vp_index array prior to derefencing hv_vp_index when\nsetting Hyper-V's TSC change callback.  If Hyper-V setup failed in\nhyperv_init(), the kernel will still report that it's running under\nHyper-V, but will have silently disabled nearly all functionality.\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000010\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 0 P4D 0\n  Oops: 0000 [#1] SMP\n  CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc2+ #75\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:set_hv_tscchange_cb+0x15/0xa0\n  Code: <8b> 04 82 8b 15 12 17 85 01 48 c1 e0 20 48 0d ee 00 01 00 f6 c6 08\n  ...\n  Call Trace:\n   kvm_arch_init+0x17c/0x280\n   kvm_init+0x31/0x330\n   vmx_init+0xba/0x13a\n   do_one_initcall+0x41/0x1c0\n   kernel_init_freeable+0x1f2/0x23b\n   kernel_init+0x16/0x120\n   ret_from_fork+0x22/0x30","publishedAt":"2024-04-10T19:01:56.419Z","updatedAt":"2026-05-11T13:50:14.845Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"b20ec58f8a6f4fef32cc71480ddf824584e24743","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"b0e44dfb4e4c699cca33ede431b8d127e6e8d661","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"9c177eee116cf888276d3748cb176e72562cfd5c","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"8823ea27fff6084bbb4bc71d15378fae0220b1d8","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"daf972118c517b91f74ff1731417feb4270625a4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/hyperv/hv_init.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"4.19.218","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.162","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.82","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.5","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/hyperv/hv_init.c"]}],"references":["https://git.kernel.org/stable/c/b20ec58f8a6f4fef32cc71480ddf824584e24743","https://git.kernel.org/stable/c/b0e44dfb4e4c699cca33ede431b8d127e6e8d661","https://git.kernel.org/stable/c/9c177eee116cf888276d3748cb176e72562cfd5c","https://git.kernel.org/stable/c/8823ea27fff6084bbb4bc71d15378fae0220b1d8","https://git.kernel.org/stable/c/daf972118c517b91f74ff1731417feb4270625a4"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47217.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47217","state":"PUBLISHED","datePublished":"2024-04-10T19:01:56.419Z","dateUpdated":"2026-05-11T13:50:14.845Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-04-10T18:59:19.528Z"},"containers":{"cna":{"title":"x86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nx86/hyperv: Fix NULL deref in set_hv_tscchange_cb() if Hyper-V setup fails\n\nCheck for a valid hv_vp_index array prior to derefencing hv_vp_index when\nsetting Hyper-V's TSC change callback.  If Hyper-V setup failed in\nhyperv_init(), the kernel will still report that it's running under\nHyper-V, but will have silently disabled nearly all functionality.\n\n  BUG: kernel NULL pointer dereference, address: 0000000000000010\n  #PF: supervisor read access in kernel mode\n  #PF: error_code(0x0000) - not-present page\n  PGD 0 P4D 0\n  Oops: 0000 [#1] SMP\n  CPU: 4 PID: 1 Comm: swapper/0 Not tainted 5.15.0-rc2+ #75\n  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015\n  RIP: 0010:set_hv_tscchange_cb+0x15/0xa0\n  Code: <8b> 04 82 8b 15 12 17 85 01 48 c1 e0 20 48 0d ee 00 01 00 f6 c6 08\n  ...\n  Call Trace:\n   kvm_arch_init+0x17c/0x280\n   kvm_init+0x31/0x330\n   vmx_init+0xba/0x13a\n   do_one_initcall+0x41/0x1c0\n   kernel_init_freeable+0x1f2/0x23b\n   kernel_init+0x16/0x120\n   ret_from_fork+0x22/0x30"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"b20ec58f8a6f4fef32cc71480ddf824584e24743","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"b0e44dfb4e4c699cca33ede431b8d127e6e8d661","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"9c177eee116cf888276d3748cb176e72562cfd5c","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"8823ea27fff6084bbb4bc71d15378fae0220b1d8","versionType":"git"},{"version":"93286261de1b46339aa27cd4c639b21778f6cade","status":"affected","lessThan":"daf972118c517b91f74ff1731417feb4270625a4","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/hyperv/hv_init.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.16","versionType":"semver"},{"version":"4.19.218","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.162","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.82","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.5","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"5.16","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/x86/hyperv/hv_init.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/b20ec58f8a6f4fef32cc71480ddf824584e24743"},{"url":"https://git.kernel.org/stable/c/b0e44dfb4e4c699cca33ede431b8d127e6e8d661"},{"url":"https://git.kernel.org/stable/c/9c177eee116cf888276d3748cb176e72562cfd5c"},{"url":"https://git.kernel.org/stable/c/8823ea27fff6084bbb4bc71d15378fae0220b1d8"},{"url":"https://git.kernel.org/stable/c/daf972118c517b91f74ff1731417feb4270625a4"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T13:50:14.845Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"4.19.218"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.4.162"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.10.82"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.15.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.16","versionEndExcluding":"5.16"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA 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