1 files changed, 33 insertions, 16 deletions

diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 2e6fb1d758c3..a6dcfda3e11e 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -226,7 +226,9 @@ static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
 static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
                              unsigned long address)
 {
-        if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT))) {
+        /* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
+        if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
+                                      DSISR_PROTFAULT))) {
                 printk_ratelimited(KERN_CRIT "kernel tried to execute"
                                    " exec-protected page (%lx) -"
                                    "exploit attempt? (uid: %d)\n",
@@ -341,10 +343,21 @@ static inline void cmo_account_page_fault(void)
 static inline void cmo_account_page_fault(void) { }
 #endif /* CONFIG_PPC_SMLPAR */
 
-#ifdef CONFIG_PPC_STD_MMU
-static void sanity_check_fault(bool is_write, unsigned long error_code)
+#ifdef CONFIG_PPC_BOOK3S
+static void sanity_check_fault(bool is_write, bool is_user,
+                               unsigned long error_code, unsigned long address)
 {
         /*
+         * Userspace trying to access kernel address, we get PROTFAULT for that.
+         */
+        if (is_user && address >= TASK_SIZE) {
+                pr_crit_ratelimited("%s[%d]: User access of kernel address (%lx) - exploit attempt? (uid: %d)\n",
+                                   current->comm, current->pid, address,
+                                   from_kuid(&init_user_ns, current_uid()));
+                return;
+        }
+
+        /*
          * For hash translation mode, we should never get a
          * PROTFAULT. Any update to pte to reduce access will result in us
          * removing the hash page table entry, thus resulting in a DSISR_NOHPTE
@@ -373,12 +386,15 @@ static void sanity_check_fault(bool is_write, unsigned long error_code)
          * For radix, we can get prot fault for autonuma case, because radix
          * page table will have them marked noaccess for user.
          */
-        if (!radix_enabled() && !is_write)
-                WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
+        if (radix_enabled() || is_write)
+                return;
+
+        WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
 }
 #else
-static void sanity_check_fault(bool is_write, unsigned long error_code) { }
-#endif /* CONFIG_PPC_STD_MMU */
+static void sanity_check_fault(bool is_write, bool is_user,
+                               unsigned long error_code, unsigned long address) { }
+#endif /* CONFIG_PPC_BOOK3S */
 
 /*
  * Define the correct "is_write" bit in error_code based
@@ -435,7 +451,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
         }
 
         /* Additional sanity check(s) */
-        sanity_check_fault(is_write, error_code);
+        sanity_check_fault(is_write, is_user, error_code, address);
 
         /*
          * The kernel should never take an execute fault nor should it
@@ -637,21 +653,22 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
         case 0x300:
         case 0x380:
         case 0xe00:
-                printk(KERN_ALERT "Unable to handle kernel paging request for "
-                        "data at address 0x%08lx\n", regs->dar);
+                pr_alert("BUG: %s at 0x%08lx\n",
+                         regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" :
+                         "Unable to handle kernel data access", regs->dar);
                 break;
         case 0x400:
         case 0x480:
-                printk(KERN_ALERT "Unable to handle kernel paging request for "
-                        "instruction fetch\n");
+                pr_alert("BUG: Unable to handle kernel instruction fetch%s",
+                         regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n");
                 break;
         case 0x600:
-                printk(KERN_ALERT "Unable to handle kernel paging request for "
-                        "unaligned access at address 0x%08lx\n", regs->dar);
+                pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n",
+                         regs->dar);
                 break;
         default:
-                printk(KERN_ALERT "Unable to handle kernel paging request for "
-                        "unknown fault\n");
+                pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n",
+                         regs->dar);
                 break;
         }
         printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",