Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: arm64: make huge_ptep_get handled unaligned addresses huge_ptep_get() can be handed a virtual address pointing to the middle of a contpmd/contpte mapped hugetlb folio (examples of callers are pagemap_hugetlb_range, page_mapped_in_vma). The arm64 helper rewalks the pgtables in find_num_contig to answer whether the huge pte we have maps a contpmd or a contpte hugetlb folio, and returns CONT_PMDS or CONT_PTES, so that it can collect a/d bits over the contiguous ptes. We can falsely return CONT_PTES instead of CONT_PMDS if the addr is not aligned. On systems where CONT_PTES != CONT_PMDS (meaning page size is 16K), we could collect excess A/D bit state, meaning extra work for the kernel. Even worse, we may iterate beyond the PTE table and dereference a garbage ptep pointer to access physical memory we don't own. Since the ptep pointer is a linear map address, we may run off the end of the linear map or into a hole, dereference a VA not mapped into the kernel pgtables and cause kernel panic. Fix this by aligning the pmdp pointer down to a contpmd base before checking equality with the passed huge pte pointer, to correctly answer whether the huge pte is the base of a contpmd block.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 29cb80519689706387bde47000dbb2ed91143063 before 9cd4b1a52eff330798d668c1775f8bc450776280; affected 29cb80519689706387bde47000dbb2ed91143063 before f3530aec26563f4d483ff31402392961362e9bc6; affected 29cb80519689706387bde47000dbb2ed91143063 before f73a8edc2ccc6ec72c37d5c578e7592d2e1f9922 |
| Linux / Linux | affected 6.16; unaffected 0 before 6.16; unaffected 6.18.42 through 6.18.*; unaffected 7.1.6 through 7.1.*; unaffected 7.2 through * |
CWE
No CWE identifiers supplied.