Commit 6e554abd authored by Will Deacon's avatar Will Deacon Committed by Catalin Marinas
Browse files

arm64: compat: Poison the compat sigpage 



Commit 9c698bff ("ARM: ensure the signal page contains defined contents")
poisoned the unused portions of the signal page for 32-bit Arm.

Implement the same poisoning for the compat signal page on arm64 rather
than using __GFP_ZERO.

Signed-off-by: default avatarWill Deacon <will@kernel.org>
Reviewed-by: default avatarVincenzo Frascino <vincenzo.frascino@arm.com>
Link: https://lore.kernel.org/r/20210318170738.7756-6-will@kernel.org


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 77ec4625

arch/arm64/kernel/vdso.c

+6 −3
Original line number Diff line number Diff line
@@ -318,17 +318,20 @@ static int aarch32_alloc_kuser_vdso_page(void) 
	return 0;

}



#define COMPAT_SIGPAGE_POISON_WORD	0xe7fddef1

static int aarch32_alloc_sigpage(void)

{

	extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];

	int sigret_sz = __aarch32_sigret_code_end - __aarch32_sigret_code_start;

	unsigned long sigpage;

	__le32 poison = cpu_to_le32(COMPAT_SIGPAGE_POISON_WORD);

	void *sigpage;



	sigpage = get_zeroed_page(GFP_KERNEL);

	sigpage = (void *)__get_free_page(GFP_KERNEL);

	if (!sigpage)

		return -ENOMEM;



	memcpy((void *)sigpage, __aarch32_sigret_code_start, sigret_sz);

	memset32(sigpage, (__force u32)poison, PAGE_SIZE / sizeof(poison));

	memcpy(sigpage, __aarch32_sigret_code_start, sigret_sz);

	aarch32_sig_page = virt_to_page(sigpage);

	return 0;

}