Re: [PATCH 5/5] arm64: compat: Poison the compat sigpage
From: Vincenzo Frascino <vincenzo.frascino@arm.com>
Date: 2021-03-18 18:15:23
On 3/18/21 5:07 PM, Will Deacon wrote:
Commit 9c698bff66ab ("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: Will Deacon <will@kernel.org>Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
quoted hunk ↗ jump to hunk
--- arch/arm64/kernel/vdso.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index 16bf0b46fb70..159b72a646ab 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c@@ -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; }
-- Regards, Vincenzo _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel