In the Linux kernel, the following vulnerability has been resolved: powerpc/kasan: Fix addr error caused by page alignment In kasan_init_region, when k_start is not page aligned, at the begin of for loop, k_cur = k_start & PAGE_MASK is less than k_start, and then va = block + k_cur - k_start
is less than block, the addr va is invalid, because the memory address space from va to block is not alloced by memblock_alloc, which will not be reserved by memblock_reserve later, it will be used by other places. As a result, memory overwriting occurs. for example: int __init __weak kasan_init_region(void start, size_t size) { […] / if say block(dcd97000) k_start(feef7400) k_end(feeff3fe) / block = memblock_alloc(k_end - k_start, PAGE_SIZE); […] for (k_cur = k_start & PAGE_MASK; k_cur < k_end; k_cur += PAGE_SIZE) { / at the begin of for loop * block(dcd97000) va(dcd96c00) k_cur(feef7000) k_start(feef7400) * va(dcd96c00) is less than block(dcd97000), va is invalid */ void *va = block + k_cur - k_start; […] } […] } Therefore, page alignment is performed on k_start before memblock_alloc() to ensure the validity of the VA address.
OS | Version | Architecture | Package | Version | Filename |
---|---|---|---|---|---|
Debian | 12 | all | linux | < 6.1.82-1 | linux_6.1.82-1_all.deb |
Debian | 11 | all | linux | < 5.10.216-1 | linux_5.10.216-1_all.deb |
Debian | 10 | all | linux | < 4.19.249-2 | linux_4.19.249-2_all.deb |
Debian | 999 | all | linux | < 6.7.7-1 | linux_6.7.7-1_all.deb |
Debian | 13 | all | linux | < 6.7.7-1 | linux_6.7.7-1_all.deb |
Debian | 10 | all | linux-5.10 | < 5.10.216-1~deb10u1 | linux-5.10_5.10.216-1~deb10u1_all.deb |