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powerpc/kasan: Force thread size increase with KASAN

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[ Upstream commit 3e8635fb2e ]

KASAN causes increased stack usage, which can lead to stack overflows.

The logic in Kconfig to suggest a larger default doesn't work if a user
has CONFIG_EXPERT enabled and has an existing .config with a smaller
value.

Follow the lead of x86 and arm64, and force the thread size to be
increased when KASAN is enabled.

That also has the effect of enlarging the stack for 64-bit KASAN builds,
which is also desirable.

Fixes: edbadaf067 ("powerpc/kasan: Fix stack overflow by increasing THREAD_SHIFT")
Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Use MIN_THREAD_SHIFT as suggested by Christophe]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220601143114.133524-1-mpe@ellerman.id.au
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Michael Ellerman 2022-06-02 00:31:14 +10:00 committed by Greg Kroah-Hartman
parent 62d9106205
commit 1fee1194e4
2 changed files with 8 additions and 3 deletions
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1
arch/powerpc/Kconfig
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@ -764,7 +764,6 @@ config THREAD_SHIFT
range 13 15
default "15" if PPC_256K_PAGES
default "14" if PPC64
default "14" if KASAN
default "13"
help
Used to define the stack size. The default is almost always what you

10
arch/powerpc/include/asm/thread_info.h
View file

@ -14,10 +14,16 @@
#ifdef __KERNEL__
#if defined(CONFIG_VMAP_STACK) && CONFIG_THREAD_SHIFT < PAGE_SHIFT
#ifdef CONFIG_KASAN
#define MIN_THREAD_SHIFT (CONFIG_THREAD_SHIFT + 1)
#else
#define MIN_THREAD_SHIFT CONFIG_THREAD_SHIFT
#endif
#if defined(CONFIG_VMAP_STACK) && MIN_THREAD_SHIFT < PAGE_SHIFT
#define THREAD_SHIFT PAGE_SHIFT
#else
#define THREAD_SHIFT CONFIG_THREAD_SHIFT
#define THREAD_SHIFT MIN_THREAD_SHIFT
#endif
#define THREAD_SIZE (1 << THREAD_SHIFT)