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.

Classification

CVE ID: CVE-2024-26712

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 12.41% (scored less or equal to compared to others)

EPSS Date: 2025-02-04 (when was this score calculated)

References

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

Timeline