{"id":"CVE-2026-98214","summary":"selinux: recheck intermediate backing files on mprotect()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nselinux: recheck intermediate backing files on mprotect()\n\nmprotect() can be used to bypass the SELinux checks that mmap() performs\nagainst the intermediate layers of a stacked filesystem.\n\nmmap() checks every backing layer as the request descends through the\nstack.  mprotect() only has the lowest backing file in vma-\u003evm_file, so it\nrechecks the top-level user and the lowest mounter, but skips the mounters\nof every layer in between.  With two nested overlayfs mounts and a policy\ndenying mounter_t -\u003e middle_file_t:file { execute }, a direct\nmmap(PROT_EXEC) is denied:\n\n  avc:  denied  { execute } for  pid=71 comm=\"nested_exec\"\n    path=\"/payload\" dev=\"overlay\" ino=9\n    scontext=user_u:base_r:mounter_t\n    tcontext=user_u:object_r:middle_file_t tclass=file permissive=0\n\nwhile mmap(PROT_NONE) followed by mprotect(PROT_EXEC) succeeds.\n\nPreserve each intermediate path, mounter SID and file-description SID in\nthe backing-file security blob, copying the saved entries when another\nbacking layer is opened.  Allocate the array only for nested backing files,\nand release it and the path references in the backing_file_free hook.\n\nDuring mprotect(), recheck fd { use } and the requested inode permissions\nfor every saved mounter, and include the intermediate layers in the execmod\nchecks.  Policy for nested stacking may then need to grant intermediate\nmounters what a direct mmap() already requires, and execmod on intermediate\nlabels for binaries using text relocations.\n\nTested on arm64 QEMU with a small BusyBox initramfs and a purpose-built\nSELinux policy, on a mainline tree containing\ncommit f2381b546e7e (\"fs: fix user path of nested backing files\").\n\n[PM: subject tweak]","modified":"2026-10-08T02:52:54.193330717Z","published":"2026-10-06T08:44:50.209Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98214.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/4d50ebe5a27724e020747ffd61a051dec67cb8ec"},{"type":"WEB","url":"https://git.kernel.org/stable/c/78fc54b934bfb2c18aad8154c7302067146946f9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/89376fbfdcc1a728e1775f98752cdd90b0930a00"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c2bbb905af2293549651b614a52ad91e0b462b60"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d127c7e1f3e1231d8ac8b2738e3f00bea12afe74"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98214.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98214"},{"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":"bc6c380c1159de52a252ed11f19a42c47f60a735"},{"fixed":"4d50ebe5a27724e020747ffd61a051dec67cb8ec"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"8bacd09f12c27710228562e4d13163e58c5f4a45"},{"fixed":"89376fbfdcc1a728e1775f98752cdd90b0930a00"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"d844702198395d3f80222777030f69db6be6b709"},{"fixed":"d127c7e1f3e1231d8ac8b2738e3f00bea12afe74"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"82544d36b1729153c8aeb179e84750f0c085d3b1"},{"fixed":"c2bbb905af2293549651b614a52ad91e0b462b60"},{"fixed":"78fc54b934bfb2c18aad8154c7302067146946f9"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.6.144"},{"fixed":"6.6.158"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.12.95"},{"fixed":"6.12.112"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.18.38"},{"fixed":"6.18.54"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7.0.4"},{"fixed":"7.1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"cd0e707a927a70cdfd8bc5a512a9719a87f5ed51"}]}],"versions":["v6.6.157","v6.6.156","v6.6.155","v6.6.154","v6.6.153","v6.6.152","v6.6.151","v6.6.150","v6.6.149","v6.6.148","v6.6.147","v6.6.146","v6.6.145","v6.6.144","v6.12.111","v6.12.110","v6.12.109","v6.12.108","v6.12.107","v6.12.106","v6.12.105","v6.12.104","v6.12.103","v6.12.102","v6.12.101","v6.12.100","v6.12.99","v6.12.98","v6.12.97","v6.12.96","v6.12.95","v6.18.53","v6.18.52","v6.18.51","v6.18.50","v6.18.49","v6.18.48","v6.18.47","v6.18.46","v6.18.45","v6.18.44","v6.18.43","v6.18.42","v6.18.41","v6.18.40","v6.18.39","v6.18.38","v7.0.14","v7.0.13","v7.0.12","v7.0.11","v7.0.10","v7.0.9","v7.0.8","v7.0.7","v7.0.6","v7.0.5","v7.0.4"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98214.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.158"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.112"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.54"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.8"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98214.json"}}],"schema_version":"1.9.0"}