diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c index 4c64d90155c10aea6ed757aaa85c553a6048b37f..be30efcbaf7d39639934c5008506951a836e5334 100644 --- a/arch/arm/mm/fault.c +++ b/arch/arm/mm/fault.c @@ -131,6 +131,19 @@ static inline bool is_translation_fault(unsigned int fsr) return false; } +static inline bool is_permission_fault(unsigned int fsr) +{ + int fs = fsr_fs(fsr); +#ifdef CONFIG_ARM_LPAE + if ((fs & FS_MMU_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) @@ -165,6 +178,8 @@ __do_kernel_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr, */ if (addr < PAGE_SIZE) { msg = "NULL pointer dereference"; + } else if (is_permission_fault(fsr) && fsr & FSR_LNX_PF) { + msg = "execution of memory"; } else { if (is_translation_fault(fsr) && kfence_handle_page_fault(addr, is_write_fault(fsr), regs)) @@ -231,19 +246,6 @@ void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs) #define VM_FAULT_BADMAP 0x010000 #define VM_FAULT_BADACCESS 0x020000 -static inline bool is_permission_fault(unsigned int fsr) -{ - int fs = fsr_fs(fsr); -#ifdef CONFIG_ARM_LPAE - if ((fs & FS_MMU_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) @@ -271,6 +273,35 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int flags, return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs); } +static int __kprobes +do_kernel_address_page_fault(struct mm_struct *mm, unsigned long addr, + unsigned int fsr, struct pt_regs *regs) +{ + if (user_mode(regs)) { + /* + * Fault from user mode for a kernel space address. User mode + * should not be faulting in kernel space, which includes the + * vector/khelper page. Send a SIGSEGV. + */ + __do_user_fault(addr, fsr, SIGSEGV, SEGV_MAPERR, regs); + } else { + /* + * Fault from kernel mode. Enable interrupts if they were + * enabled in the parent context. Section (upper page table) + * translation faults are handled via do_translation_fault(), + * so we will only get here for a non-present kernel space + * PTE or PTE permission fault. This may happen in exceptional + * circumstances and need the fixup tables to be walked. + */ + if (interrupts_enabled(regs)) + local_irq_enable(); + + __do_kernel_fault(mm, addr, fsr, regs); + } + + return 0; +} + static int __kprobes do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) { @@ -283,6 +314,12 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs) if (kprobe_page_fault(regs, fsr)) return 0; + /* + * Handle kernel addresses faults separately, which avoids touching + * the mmap lock from contexts that are not able to sleep. + */ + if (addr >= TASK_SIZE) + return do_kernel_address_page_fault(mm, addr, fsr, regs); /* Enable interrupts if they were enabled in the parent context. */ if (interrupts_enabled(regs))