title: powerpc/kasan: Limit KASAN thread size increase to 32KB
description: 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:
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 9ccf64e763ac, lessThan: 4297217bcf1f, status: affected, versionType: git
version: b38014874530, lessThan: 4cc31fa07445, status: affected, versionType: git
version: 58f396513cb1, lessThan: b29b16bd836a, status: affected, versionType: git
version: 18f14afe2816, lessThan: f1acb109505d, status: affected, versionType: git
}
{
product: Linux
vendor: Linux
defaultStatus: unaffected
repo: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
versions:
version: 6.1.75, lessThan: 6.1.79, status: affected, versionType: custom
version: 6.6.14, lessThan: 6.6.18, status: affected, versionType: custom
version: 6.7.2, lessThan: 6.7.6, status: affected, versionType: custom
}
