ACK: [SRU][M][PATCH 0/1] CVE-2024-26710

[Andrei Gherzan]

On 24/04/19 03:49PM, Bethany Jamison wrote:
> [Impact]
> 
>  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.
> 
> [Fix]
> 
> Mantic:	Clean cherry-pick from linux-6.6.y
> Jammy:	not-affected
> Focal:	not-affected
> Bionic:	not-affected
> Xenial:	not-affected
> Trusty:	not-affected
> 
> [Test Case]
> 
> Compile and boot tested.
> 
> [Where problems could occur]
> 
> This fix affects those who use KASAN on PowerPC, an issue with this 
> fix would be visable to the user via a system crash.
> 
> Michael Ellerman (1):
>   powerpc/kasan: Limit KASAN thread size increase to 32KB
> 
>  arch/powerpc/include/asm/thread_info.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Andrei Gherzan <andrei.gherzan at canonical.com>

-- 
Andrei Gherzan
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