Messages in this thread Patch in this message | | | From | Kefeng Wang <> | Subject | [PATCH v2] ARM: mm: Provide better fault message for permission fault | Date | Mon, 19 Sep 2022 18:38:45 +0800 |
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If there is a permission fault in __do_kernel_fault(), we only print the generic "paging request" message which don't show read, write or excute information, let's provide better fault message for them.
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> --- v2: fix !CONFIG_MMU built
arch/arm/mm/fault.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 46cccd6bf705..387c87112d80 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -105,6 +105,19 @@ static inline bool is_write_fault(unsigned int fsr) return (fsr & FSR_WRITE) && !(fsr & FSR_CM); } +static inline bool is_permission_fault(unsigned int fsr) +{ + int fs = fsr_fs(fsr); +#ifdef CONFIG_ARM_LPAE + if ((fs & FS_PERM_NOLL_MASK) == FS_PERM_NOLL) + return true; +#else + if (fs == FS_L1_PERM || fs == FS_L2_PERM) + return true; +#endif + return false; +} + static void die_kernel_fault(const char *msg, struct mm_struct *mm, unsigned long addr, unsigned int fsr, struct pt_regs *regs) @@ -137,7 +150,14 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, /* * No handler, we'll have to terminate things with extreme prejudice. */ - if (addr < PAGE_SIZE) { + if (is_permission_fault(fsr)) { + if (fsr & FSR_WRITE) + msg = "write to read-only memory"; + else if (fsr & FSR_LNX_PF) + msg = "execute from non-executable memory"; + else + msg = "read from unreadable memory"; + } else if (addr < PAGE_SIZE) { msg = "NULL pointer dereference"; } else { if (kfence_handle_page_fault(addr, is_write_fault(fsr), regs)) @@ -204,19 +224,6 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) #define VM_FAULT_BADMAP ((__force vm_fault_t)0x010000) #define VM_FAULT_BADACCESS ((__force vm_fault_t)0x020000) -static inline bool is_permission_fault(unsigned int fsr) -{ - int fs = fsr_fs(fsr); -#ifdef CONFIG_ARM_LPAE - if ((fs & FS_PERM_NOLL_MASK) == FS_PERM_NOLL) - return true; -#else - if (fs == FS_L1_PERM || fs == FS_L2_PERM) - return true; -#endif - return false; -} - static vm_fault_t __kprobes __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags, unsigned long vma_flags, struct pt_regs *regs) -- 2.35.3
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