Messages in this thread Patch in this message | | | From | Kefeng Wang <> | Subject | [PATCH v2 7/7] ARM: mm: Fix PXN process with LPAE feature | Date | Wed, 2 Jun 2021 15:02:46 +0800 |
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When user code execution with privilege mode, it will lead to infinite loop in the page fault handler if ARM_LPAE enabled,
The issue could be reproduced with "echo EXEC_USERSPACE > /sys/kernel/debug/provoke-crash/DIRECT"
Lets' fix it by adding the check in do_page_fault() and panic when ARM_LPAE enabled.
Fixes: 1d4d37159d01 ("ARM: 8235/1: Support for the PXN CPU feature on ARMv7") Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> --- arch/arm/mm/fault.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 7cfa9a59d3ec..279bbeb33b48 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -257,8 +257,14 @@ 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 && addr < TASK_SIZE && !user_mode(regs)) + die_kernel_fault("execution of user memory", + addr, fsr, regs); +#endif + } perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr); -- 2.26.2
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