1 files changed, 75 insertions, 25 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index da2ccf142358..2d988141ab85 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -978,18 +978,36 @@ static int prepare_kprobe(struct kprobe *p)
 }
 
 /* Caller must lock kprobe_mutex */
-static void arm_kprobe_ftrace(struct kprobe *p)
+static int arm_kprobe_ftrace(struct kprobe *p)
 {
-        int ret;
+        int ret = 0;
 
         ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
                                    (unsigned long)p->addr, 0, 0);
-        WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
-        kprobe_ftrace_enabled++;
-        if (kprobe_ftrace_enabled == 1) {
+        if (ret) {
+                pr_debug("Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
+                return ret;
+        }
+
+        if (kprobe_ftrace_enabled == 0) {
                 ret = register_ftrace_function(&kprobe_ftrace_ops);
-                WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
+                if (ret) {
+                        pr_debug("Failed to init kprobe-ftrace (%d)\n", ret);
+                        goto err_ftrace;
+                }
         }
+
+        kprobe_ftrace_enabled++;
+        return ret;
+
+err_ftrace:
+        /*
+         * Note: Since kprobe_ftrace_ops has IPMODIFY set, and ftrace requires a
+         * non-empty filter_hash for IPMODIFY ops, we're safe from an accidental
+         * empty filter_hash which would undesirably trace all functions.
+         */
+        ftrace_set_filter_ip(&kprobe_ftrace_ops, (unsigned long)p->addr, 1, 0);
+        return ret;
 }
 
 /* Caller must lock kprobe_mutex */
@@ -1008,22 +1026,23 @@ static void disarm_kprobe_ftrace(struct kprobe *p)
 }
 #else   /* !CONFIG_KPROBES_ON_FTRACE */
 #define prepare_kprobe(p)       arch_prepare_kprobe(p)
-#define arm_kprobe_ftrace(p)    do {} while (0)
+#define arm_kprobe_ftrace(p)    (-ENODEV)
 #define disarm_kprobe_ftrace(p) do {} while (0)
 #endif
 
 /* Arm a kprobe with text_mutex */
-static void arm_kprobe(struct kprobe *kp)
+static int arm_kprobe(struct kprobe *kp)
 {
-        if (unlikely(kprobe_ftrace(kp))) {
-                arm_kprobe_ftrace(kp);
-                return;
-        }
+        if (unlikely(kprobe_ftrace(kp)))
+                return arm_kprobe_ftrace(kp);
+
         cpus_read_lock();
         mutex_lock(&text_mutex);
         __arm_kprobe(kp);
         mutex_unlock(&text_mutex);
         cpus_read_unlock();
+
+        return 0;
 }
 
 /* Disarm a kprobe with text_mutex */
@@ -1362,9 +1381,15 @@ out:
 
         if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
                 ap->flags &= ~KPROBE_FLAG_DISABLED;
-                if (!kprobes_all_disarmed)
+                if (!kprobes_all_disarmed) {
                         /* Arm the breakpoint again. */
-                        arm_kprobe(ap);
+                        ret = arm_kprobe(ap);
+                        if (ret) {
+                                ap->flags |= KPROBE_FLAG_DISABLED;
+                                list_del_rcu(&p->list);
+                                synchronize_sched();
+                        }
+                }
         }
         return ret;
 }
@@ -1573,8 +1598,14 @@ int register_kprobe(struct kprobe *p)
         hlist_add_head_rcu(&p->hlist,
                        &kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
 
-        if (!kprobes_all_disarmed && !kprobe_disabled(p))
-                arm_kprobe(p);
+        if (!kprobes_all_disarmed && !kprobe_disabled(p)) {
+                ret = arm_kprobe(p);
+                if (ret) {
+                        hlist_del_rcu(&p->hlist);
+                        synchronize_sched();
+                        goto out;
+                }
+        }
 
         /* Try to optimize kprobe */
         try_to_optimize_kprobe(p);
@@ -2116,7 +2147,9 @@ int enable_kprobe(struct kprobe *kp)
 
         if (!kprobes_all_disarmed && kprobe_disabled(p)) {
                 p->flags &= ~KPROBE_FLAG_DISABLED;
-                arm_kprobe(p);
+                ret = arm_kprobe(p);
+                if (ret)
+                        p->flags |= KPROBE_FLAG_DISABLED;
         }
 out:
         mutex_unlock(&kprobe_mutex);
@@ -2407,11 +2440,12 @@ static const struct file_operations debugfs_kprobe_blacklist_ops = {
         .release        = seq_release,
 };
 
-static void arm_all_kprobes(void)
+static int arm_all_kprobes(void)
 {
         struct hlist_head *head;
         struct kprobe *p;
-        unsigned int i;
+        unsigned int i, total = 0, errors = 0;
+        int err, ret = 0;
 
         mutex_lock(&kprobe_mutex);
 
@@ -2428,16 +2462,28 @@ static void arm_all_kprobes(void)
         /* Arming kprobes doesn't optimize kprobe itself */
         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                 head = &kprobe_table[i];
-                hlist_for_each_entry_rcu(p, head, hlist)
-                        if (!kprobe_disabled(p))
-                                arm_kprobe(p);
+                /* Arm all kprobes on a best-effort basis */
+                hlist_for_each_entry_rcu(p, head, hlist) {
+                        if (!kprobe_disabled(p)) {
+                                err = arm_kprobe(p);
+                                if (err)  {
+                                        errors++;
+                                        ret = err;
+                                }
+                                total++;
+                        }
+                }
         }
 
-        printk(KERN_INFO "Kprobes globally enabled\n");
+        if (errors)
+                pr_warn("Kprobes globally enabled, but failed to arm %d out of %d probes\n",
+                        errors, total);
+        else
+                pr_info("Kprobes globally enabled\n");
 
 already_enabled:
         mutex_unlock(&kprobe_mutex);
-        return;
+        return ret;
 }
 
 static void disarm_all_kprobes(void)
@@ -2494,6 +2540,7 @@ static ssize_t write_enabled_file_bool(struct file *file,
 {
         char buf[32];
         size_t buf_size;
+        int ret = 0;
 
         buf_size = min(count, (sizeof(buf)-1));
         if (copy_from_user(buf, user_buf, buf_size))
@@ -2504,7 +2551,7 @@ static ssize_t write_enabled_file_bool(struct file *file,
         case 'y':
         case 'Y':
         case '1':
-                arm_all_kprobes();
+                ret = arm_all_kprobes();
                 break;
         case 'n':
         case 'N':
@@ -2515,6 +2562,9 @@ static ssize_t write_enabled_file_bool(struct file *file,
                 return -EINVAL;
         }
 
+        if (ret)
+                return ret;
+
         return count;
 }