{"id":"CVE-2025-39817","summary":"efivarfs: Fix slab-out-of-bounds in efivarfs_d_compare","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nefivarfs: Fix slab-out-of-bounds in efivarfs_d_compare\n\nObserved on kernel 6.6 (present on master as well):\n\n  BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0\n  Call trace:\n   kasan_check_range+0xe8/0x190\n   __asan_loadN+0x1c/0x28\n   memcmp+0x98/0xd0\n   efivarfs_d_compare+0x68/0xd8\n   __d_lookup_rcu_op_compare+0x178/0x218\n   __d_lookup_rcu+0x1f8/0x228\n   d_alloc_parallel+0x150/0x648\n   lookup_open.isra.0+0x5f0/0x8d0\n   open_last_lookups+0x264/0x828\n   path_openat+0x130/0x3f8\n   do_filp_open+0x114/0x248\n   do_sys_openat2+0x340/0x3c0\n   __arm64_sys_openat+0x120/0x1a0\n\nIf dentry-\u003ed_name.len \u003c EFI_VARIABLE_GUID_LEN , 'guid' can become\nnegative, leadings to oob. The issue can be triggered by parallel\nlookups using invalid filename:\n\n  T1\t\t\tT2\n  lookup_open\n   -\u003elookup\n    simple_lookup\n     d_add\n     // invalid dentry is added to hash list\n\n\t\t\tlookup_open\n\t\t\t d_alloc_parallel\n\t\t\t  __d_lookup_rcu\n\t\t\t   __d_lookup_rcu_op_compare\n\t\t\t    hlist_bl_for_each_entry_rcu\n\t\t\t    // invalid dentry can be retrieved\n\t\t\t     -\u003ed_compare\n\t\t\t      efivarfs_d_compare\n\t\t\t      // oob\n\nFix it by checking 'guid' before cmp.","modified":"2026-03-27T08:59:22.422569Z","published":"2025-09-16T13:00:17.776Z","related":["ALSA-2025:18281","ALSA-2025:18318","ALSA-2025:19102","ALSA-2025:19103","SUSE-SU-2026:0962-1","SUSE-SU-2026:1041-1","SUSE-SU-2026:1078-1","SUSE-SU-2026:1081-1","SUSE-SU-2026:20555-1","SUSE-SU-2026:20599-1","SUSE-SU-2026:20615-1","openSUSE-SU-2026:20287-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39817.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/568e7761279b99c6daa3002290fd6d8047ddb6d2"},{"type":"WEB","url":"https://git.kernel.org/stable/c/71581a82f38e5a4d807d71fc1bb59aead80ccf95"},{"type":"WEB","url":"https://git.kernel.org/stable/c/794399019301944fd6d2e0d7a51b3327e26c410e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/925599eba46045930b850a98ae594d2e3028ac40"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a6358f8cf64850f3f27857b8ed8c1b08cfc4685c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c2925cd6207079c3f4d040d082515db78d63afbf"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39817.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39817"},{"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":"da27a24383b2b10bf6ebd0db29b325548aafecb4"},{"fixed":"0f63fbabeaaaaaaf5b742a2f4c1b4590d50bf1f6"},{"fixed":"794399019301944fd6d2e0d7a51b3327e26c410e"},{"fixed":"568e7761279b99c6daa3002290fd6d8047ddb6d2"},{"fixed":"d7f5e35e70507d10cbaff5f9e194ed54c4ee14f7"},{"fixed":"925599eba46045930b850a98ae594d2e3028ac40"},{"fixed":"c2925cd6207079c3f4d040d082515db78d63afbf"},{"fixed":"71581a82f38e5a4d807d71fc1bb59aead80ccf95"},{"fixed":"a6358f8cf64850f3f27857b8ed8c1b08cfc4685c"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0"},{"last_affected":"688289c4b745c018b3449b4b4c5a2030083c8eaf"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-39817.json"}}],"schema_version":"1.7.5"}