CVE-2024-26710

In the Linux kernel, the following vulnerability has been resolved:

powerpc/kasan: Limit KASAN thread size increase to 32KB

KASAN is seen to increase stack usage, to the point that it was reported to lead to stack overflow on some 32-bit machines (see link).

To avoid overflows the stack size was doubled for KASAN builds in commit 3e8635fb2e07 (powerpc/kasan: Force thread size increase with KASAN).

However with a 32KB stack size to begin with, the doubling leads to a 64KB stack, which causes build errors: arch/powerpc/kernel/switch.S:249: Error: operand out of range (0x000000000000fe50 is not between 0xffffffffffff8000 and 0x0000000000007fff)

Although the asm could be reworked, in practice a 32KB stack seems sufficient even for KASAN builds - the additional usage seems to be in the 2-3KB range for a 64-bit KASAN build.

So only increase the stack for KASAN if the stack size is < 32KB.

Affected Software

References

• https://git.kernel.org/stable/c/4297217bcf1f0948a19c2bacc6b68d92e7778ad9
• https://git.kernel.org/stable/c/4cc31fa07445879a13750cb061bb8c2654975fcb
• https://git.kernel.org/stable/c/b29b16bd836a838b7690f80e37f8376414c74cbe
• https://git.kernel.org/stable/c/f1acb109505d983779bbb7e20a1ee6244d2b5736