CVE-2021-47623: powerpc/fixmap: Fix VM debug warning on unmap
Vulnerability summary
CVE-2021-47623 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 13.2% of scored vulnerabilities.
Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 4 · Related 3Timeline
- 16-07-2024PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: powerpc/fixmap: Fix VM debug warning on unmap Unmapping a fixmap entry is done by calling __set_fixmap() with FIXMAP_PAGE_CLEAR as flags. Today, powerpc __set_fixmap() calls map_kernel_page(). map_kernel_page() is not happy when called a second time for the same page. WARNING: CPU: 0 PID: 1 at arch/powerpc/mm/pgtable.c:194 set_pte_at+0xc/0x1e8 CPU: 0 PID: 1 Comm: swapper Not tainted 5.16.0-rc3-s3k-dev-01993-g350ff07feb7d-dirty #682 NIP: c0017cd4 LR: c00187f0 CTR: 00000010 REGS: e1011d50 TRAP: 0700 Not tainted (5.16.0-rc3-s3k-dev-01993-g350ff07feb7d-dirty) MSR: 00029032 <EE,ME,IR,DR,RI> CR: 42000208 XER: 00000000 GPR00: c0165fec e1011e10 c14c0000 c0ee2550 ff800000 c0f3d000 00000000 c001686c GPR08: 00001000 b00045a9 00000001 c0f58460 c0f50000 00000000 c0007e10 00000000 GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 GPR24: 00000000 00000000 c0ee2550 00000000 c0f57000 00000ff8 00000000 ff800000 NIP [c0017cd4] set_pte_at+0xc/0x1e8 LR [c00187f0] map_kernel_page+0x9c/0x100 Call Trace: [e1011e10] [c0736c68] vsnprintf+0x358/0x6c8 (unreliable) [e1011e30] [c0165fec] __set_fixmap+0x30/0x44 [e1011e40] [c0c13bdc] early_iounmap+0x11c/0x170 [e1011e70] [c0c06cb0] ioremap_legacy_serial_console+0x88/0xc0 [e1011e90] [c0c03634] do_one_initcall+0x80/0x178 [e1011ef0] [c0c0385c] kernel_init_freeable+0xb4/0x250 [e1011f20] [c0007e34] kernel_init+0x24/0x140 [e1011f30] [c0016268] ret_from_kernel_thread+0x5c/0x64 Instruction dump: 7fe3fb78 48019689 80010014 7c630034 83e1000c 5463d97e 7c0803a6 38210010 4e800020 81250000 712a0001 41820008 <0fe00000> 9421ffe0 93e1001c 48000030 Implement unmap_kernel_page() which clears an existing pte.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- OSV · DebianEcosystem advisory · calculated5.5MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
EPSS trend
Probability
0.22%
Chance of exploitation in the next 30 days
Percentile
13%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.22% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeNo weakness data has been published for this record.
Affected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu95 products
- linuxAll versions (No fix recorded)
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded)
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 265c3491c4bc8d40587996d6ee2f447a7ccfb4f3, < 67baac10dd5ad1e9f50e8f2659984b3b0728d54e | ≥ 265c3491c4bc8d40587996d6ee2f447a7ccfb4f3, < 43ae0ccc4d2722b833fb59b905af129428e06d03 | ≥ 265c3491c4bc8d40587996d6ee2f447a7ccfb4f3, < 033fd42c18d9b2121595b6f1e8419a115f9ac5b7 | ≥ 265c3491c4bc8d40587996d6ee2f447a7ccfb4f3, < aec982603aa8cc0a21143681feb5f60ecc69d718 | 5.5
- linux_kernel< 5.10.101 | ≥ 5.11, < 5.15.24 | ≥ 5.16, < 5.16.10 | 5.17:rc1
Debian1 product
- linux< 5.16.10-1
3 vendors · 98 products
