CVE-2024-26712 Information

Description

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.

Reference

https://git.kernel.org/stable/c/230e89b5ad0a33f530a2a976b3e5e4385cb27882 https://git.kernel.org/stable/c/2738e0aa2fb24a7ab9c878d912dc2b239738c6c6 https://git.kernel.org/stable/c/0c09912dd8387e228afcc5e34ac5d79b1e3a1058 https://git.kernel.org/stable/c/0516c06b19dc64807c10e01bb99b552bdf2d7dbe https://git.kernel.org/stable/c/70ef2ba1f4286b2b73675aeb424b590c92d57b25 https://git.kernel.org/stable/c/4a7aee96200ad281a5cc4cf5c7a2e2a49d2b97b0