In the Linux kernel, the following vulnerability has been resolved: efivarfs: Fix slab-out-of-bounds in efivarfsdcompare Observed on kernel 6.6 (present on master as well): BUG: KASAN: slab-out-of-bounds in memcmp+0x98/0xd0 Call trace: kasancheckrange+0xe8/0x190 _asanloadN+0x1c/0x28 memcmp+0x98/0xd0 efivarfsdcompare+0x68/0xd8 _dlookuprcuopcompare+0x178/0x218 _dlookuprcu+0x1f8/0x228 dallocparallel+0x150/0x648 lookupopen.isra.0+0x5f0/0x8d0 openlastlookups+0x264/0x828 pathopenat+0x130/0x3f8 dofilpopen+0x114/0x248 dosysopenat2+0x340/0x3c0 _arm64sysopenat+0x120/0x1a0 If dentry->dname.len < EFIVARIABLEGUIDLEN , 'guid' can become negative, leadings to oob. The issue can be triggered by parallel lookups using invalid filename: T1 T2 lookupopen ->lookup simplelookup dadd // invalid dentry is added to hash list lookupopen dallocparallel _dlookuprcu _dlookuprcuopcompare hlistblforeachentryrcu // invalid dentry can be retrieved ->dcompare efivarfsd_compare // oob Fix it by checking 'guid' before cmp.