linux-kernel - [PATCH 2/2] ARM: mm: Fix PXN process when ARM

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Date:   Sat, 29 May 2021 11:41:38 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Russell King <linux@...linux.org.uk>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     Catalin Marinas <catalin.marinas@....com>,
        <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jungseung Lee <js07.lee@...il.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH 2/2] ARM: mm: Fix PXN process when ARM_LPAE enabled

If we support PXN feature, should panic when user code execution
with privilege mode, but it is not true when LAPE enabled, let's
fix it by adding the check in do_page_fault().

Fixes: 1d4d37159d01 ("ARM: 8235/1: Support for the PXN CPU feature on ARMv7")
Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 arch/arm/mm/fault.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 81cf3e6e2a3d..a6ada914cdf5 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -241,8 +241,13 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 		vm_flags = VM_WRITE;
 	}
 
-	if (fsr & FSR_LNX_PF)
+	if (fsr & FSR_LNX_PF) {
 		vm_flags = VM_EXEC;
+#ifdef CONFIG_ARM_LPAE
+		if (addr < TASK_SIZE && !user_mode(regs))
+			__do_kernel_fault(mm, addr, fsr, regs);
+#endif
+	}
 
 	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
 
-- 
2.26.2