CVE-2026-31575

01/Description

In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: fix hugetlb fault mutex hash calculation In mfill_atomic_hugetlb(), linear_page_index() is used to calculate the page index for hugetlb_fault_mutex_hash(). However, linear_page_index() returns the index in PAGE_SIZE units, while hugetlb_fault_mutex_hash() expects the index in huge page units. This mismatch means that different addresses within the same huge page can produce different hash values, leading to the use of different mutexes for the same huge page. This can cause races between faulting threads, which can corrupt the reservation map and trigger the BUG_ON in resv_map_release(). Fix this by introducing hugetlb_linear_page_index(), which returns the page index in huge page granularity, and using it in place of linear_page_index().

02/Affected products

linux: linux kernel

03/References5

• git.kernel.org/stable/c/0217c7fb4de4a40cee667eb21901f3204effe5ac Patch
• git.kernel.org/stable/c/08282b1bf74c69fc8ecd25493e7fdb5460f01290 Patch
• git.kernel.org/stable/c/574501ede47ac439afd67ba9812bc66722d500ba Patch
• git.kernel.org/stable/c/5a525c43baaba0bf3063f86996ca3623b71e4172 Patch
• git.kernel.org/stable/c/f4689fc089765d36c026063fb22d23533e883eb6 Patch