In the Linux kernel, the following vulnerability has been resolved: arm64: mm: Fix lockless walks with static and dynamic page-table folding Lina reports random oopsen originating from the fast GUP code when 16K pages are used with 4-level page-tables, the fourth level being folded at runtime due to lack of LPA2. In this configuration, the generic implementation of p4d_offset_lockless() will return a ‘p4d_t *’ corresponding to the ‘pgd_t’ allocated on the stack of the caller, gup_fast_pgd_range(). This is normally fine, but when the fourth level of page-table is folded at runtime, pud_offset_lockless() will offset from the address of the ‘p4d_t’ to calculate the address of the PUD in the same page-table page. This results in a stray stack read when the ‘p4d_t’ has been allocated on the stack and can send the walker into the weeds. Fix the problem by providing our own definition of p4d_offset_lockless() when CONFIG_PGTABLE_LEVELS <= 4 which returns the real page-table pointer rather than the address of the local stack variable.
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
Debian | 12 | all | linux | < 6.1.106-3 | linux_6.1.106-3_all.deb |
Debian | 11 | all | linux | < 5.10.223-1 | linux_5.10.223-1_all.deb |
Debian | 999 | all | linux | < 6.10.3-1 | linux_6.10.3-1_all.deb |
Debian | 13 | all | linux | < 6.10.3-1 | linux_6.10.3-1_all.deb |