{"id":"CVE-2026-64130","summary":"mm/page_alloc: fix initialization of tags of the huge zero folio with init_on_free","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_alloc: fix initialization of tags of the huge zero folio with init_on_free\n\n__GFP_ZEROTAGS semantics are currently a bit weird, but effectively this\nflag is only ever set alongside __GFP_ZERO and __GFP_SKIP_KASAN.\n\nIf we run with init_on_free, we will zero out pages during\n__free_pages_prepare(), to skip zeroing on the allocation path.\n\nHowever, when allocating with __GFP_ZEROTAG set, post_alloc_hook() will\nconsequently not only skip clearing page content, but also skip clearing\ntag memory.\n\nNot clearing tags through __GFP_ZEROTAGS is irrelevant for most pages that\nwill get mapped to user space through set_pte_at() later: set_pte_at() and\nfriends will detect that the tags have not been initialized yet\n(PG_mte_tagged not set), and initialize them.\n\nHowever, for the huge zero folio, which will be mapped through a PMD\nmarked as special, this initialization will not be performed, ending up\nexposing whatever tags were still set for the pages.\n\nThe docs (Documentation/arch/arm64/memory-tagging-extension.rst) state\nthat allocation tags are set to 0 when a page is first mapped to user\nspace.  That no longer holds with the huge zero folio when init_on_free is\nenabled.\n\nFix it by decoupling __GFP_ZEROTAGS from __GFP_ZERO, passing to\ntag_clear_highpages() whether we want to also clear page content.\n\nInvert the meaning of the tag_clear_highpages() return value to have\nclearer semantics.\n\nReproduced with the huge zero folio by modifying the check_buffer_fill\narm64/mte selftest to use a 2 MiB area, after making sure that pages have\na non-0 tag set when freeing (note that, during boot, we will not actually\ninitialize tags, but only set KASAN_TAG_KERNEL in the page flags).\n\n\t$ ./check_buffer_fill\n\t1..20\n\t...\n\tnot ok 17 Check initial tags with private mapping, sync error mode and mmap memory\n\tnot ok 18 Check initial tags with private mapping, sync error mode and mmap/mprotect memory\n\t...\n\nThis code needs more cleanups; we'll tackle that next, like\ndecoupling __GFP_ZEROTAGS from __GFP_SKIP_KASAN.\n\n[akpm@linux-foundation.org: s/__GPF_ZERO/__GFP_ZERO/, per David]","modified":"2026-07-21T03:47:53.347613749Z","published":"2026-07-19T15:40:26.108Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64130.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2f2aec5120b93a8f8b52dc50cdc60dbb8aec72f6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6a288a4ddb4a994490505ab5f41c445f8e6b6467"},{"type":"WEB","url":"https://git.kernel.org/stable/c/738d18f1da3513d17b6f7bf30146cc4ac2480ffd"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64130.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64130"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"adfb6609c6809e107ded9a1cd46f519c882e64ea"},{"fixed":"738d18f1da3513d17b6f7bf30146cc4ac2480ffd"},{"fixed":"2f2aec5120b93a8f8b52dc50cdc60dbb8aec72f6"},{"fixed":"6a288a4ddb4a994490505ab5f41c445f8e6b6467"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64130.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.18.0"},{"fixed":"6.18.34"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.11"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-64130.json"}}],"schema_version":"1.7.5"}