{"cve":"CVE-2021-47623","nvd":{"published":"2024-07-16T12:15:02.483","modified":"2026-06-17T04:18:11.293","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/fixmap: Fix VM debug warning on unmap\n\nUnmapping a fixmap entry is done by calling __set_fixmap()\nwith FIXMAP_PAGE_CLEAR as flags.\n\nToday, powerpc __set_fixmap() calls map_kernel_page().\n\nmap_kernel_page() is not happy when called a second time\nfor the same page.\n\n\tWARNING: CPU: 0 PID: 1 at arch/powerpc/mm/pgtable.c:194 set_pte_at+0xc/0x1e8\n\tCPU: 0 PID: 1 Comm: swapper Not tainted 5.16.0-rc3-s3k-dev-01993-g350ff07feb7d-dirty #682\n\tNIP:  c0017cd4 LR: c00187f0 CTR: 00000010\n\tREGS: e1011d50 TRAP: 0700   Not tainted  (5.16.0-rc3-s3k-dev-01993-g350ff07feb7d-dirty)\n\tMSR:  00029032 <EE,ME,IR,DR,RI>  CR: 42000208  XER: 00000000\n\n\tGPR00: c0165fec e1011e10 c14c0000 c0ee2550 ff800000 c0f3d000 00000000 c001686c\n\tGPR08: 00001000 b00045a9 00000001 c0f58460 c0f50000 00000000 c0007e10 00000000\n\tGPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000\n\tGPR24: 00000000 00000000 c0ee2550 00000000 c0f57000 00000ff8 00000000 ff800000\n\tNIP [c0017cd4] set_pte_at+0xc/0x1e8\n\tLR [c00187f0] map_kernel_page+0x9c/0x100\n\tCall Trace:\n\t[e1011e10] [c0736c68] vsnprintf+0x358/0x6c8 (unreliable)\n\t[e1011e30] [c0165fec] __set_fixmap+0x30/0x44\n\t[e1011e40] [c0c13bdc] early_iounmap+0x11c/0x170\n\t[e1011e70] [c0c06cb0] ioremap_legacy_serial_console+0x88/0xc0\n\t[e1011e90] [c0c03634] do_one_initcall+0x80/0x178\n\t[e1011ef0] [c0c0385c] kernel_init_freeable+0xb4/0x250\n\t[e1011f20] [c0007e34] kernel_init+0x24/0x140\n\t[e1011f30] [c0016268] ret_from_kernel_thread+0x5c/0x64\n\tInstruction dump:\n\t7fe3fb78 48019689 80010014 7c630034 83e1000c 5463d97e 7c0803a6 38210010\n\t4e800020 81250000 712a0001 41820008 <0fe00000> 9421ffe0 93e1001c 48000030\n\nImplement unmap_kernel_page() which clears an existing pte.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":[],"references":["https://git.kernel.org/stable/c/033fd42c18d9b2121595b6f1e8419a115f9ac5b7","https://git.kernel.org/stable/c/43ae0ccc4d2722b833fb59b905af129428e06d03","https://git.kernel.org/stable/c/67baac10dd5ad1e9f50e8f2659984b3b0728d54e","https://git.kernel.org/stable/c/aec982603aa8cc0a21143681feb5f60ecc69d718","https://git.kernel.org/stable/c/033fd42c18d9b2121595b6f1e8419a115f9ac5b7"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:52:42.518321223+00:00"},"epss":{"cve":"CVE-2021-47623","score":0.00225,"percentile":0.13224,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}