1 files changed, 119 insertions, 40 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index a1e233a19586..cb732a9aa55f 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -327,7 +327,7 @@ static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
         struct kprobe *kp;
 
         list_for_each_entry_rcu(kp, &p->list, list) {
-                if (kp->pre_handler) {
+                if (kp->pre_handler && !kprobe_gone(kp)) {
                         set_kprobe_instance(kp);
                         if (kp->pre_handler(kp, regs))
                                 return 1;
@@ -343,7 +343,7 @@ static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
         struct kprobe *kp;
 
         list_for_each_entry_rcu(kp, &p->list, list) {
-                if (kp->post_handler) {
+                if (kp->post_handler && !kprobe_gone(kp)) {
                         set_kprobe_instance(kp);
                         kp->post_handler(kp, regs, flags);
                         reset_kprobe_instance();
@@ -545,9 +545,10 @@ static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
         ap->addr = p->addr;
         ap->pre_handler = aggr_pre_handler;
         ap->fault_handler = aggr_fault_handler;
-        if (p->post_handler)
+        /* We don't care the kprobe which has gone. */
+        if (p->post_handler && !kprobe_gone(p))
                 ap->post_handler = aggr_post_handler;
-        if (p->break_handler)
+        if (p->break_handler && !kprobe_gone(p))
                 ap->break_handler = aggr_break_handler;
 
         INIT_LIST_HEAD(&ap->list);
@@ -566,17 +567,41 @@ static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
         int ret = 0;
         struct kprobe *ap;
 
+        if (kprobe_gone(old_p)) {
+                /*
+                 * Attempting to insert new probe at the same location that
+                 * had a probe in the module vaddr area which already
+                 * freed. So, the instruction slot has already been
+                 * released. We need a new slot for the new probe.
+                 */
+                ret = arch_prepare_kprobe(old_p);
+                if (ret)
+                        return ret;
+        }
         if (old_p->pre_handler == aggr_pre_handler) {
                 copy_kprobe(old_p, p);
                 ret = add_new_kprobe(old_p, p);
+                ap = old_p;
         } else {
                 ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
-                if (!ap)
+                if (!ap) {
+                        if (kprobe_gone(old_p))
+                                arch_remove_kprobe(old_p);
                         return -ENOMEM;
+                }
                 add_aggr_kprobe(ap, old_p);
                 copy_kprobe(ap, p);
                 ret = add_new_kprobe(ap, p);
         }
+        if (kprobe_gone(old_p)) {
+                /*
+                 * If the old_p has gone, its breakpoint has been disarmed.
+                 * We have to arm it again after preparing real kprobes.
+                 */
+                ap->flags &= ~KPROBE_FLAG_GONE;
+                if (kprobe_enabled)
+                        arch_arm_kprobe(ap);
+        }
         return ret;
 }
 
@@ -639,8 +664,7 @@ static int __kprobes __register_kprobe(struct kprobe *p,
                 return -EINVAL;
         }
 
-        p->mod_refcounted = 0;
-
+        p->flags = 0;
         /*
          * Check if are we probing a module.
          */
@@ -649,16 +673,14 @@ static int __kprobes __register_kprobe(struct kprobe *p,
                 struct module *calling_mod;
                 calling_mod = __module_text_address(called_from);
                 /*
-                 * We must allow modules to probe themself and in this case
-                 * avoid incrementing the module refcount, so as to allow
-                 * unloading of self probing modules.
+                 * We must hold a refcount of the probed module while updating
+                 * its code to prohibit unexpected unloading.
                  */
                 if (calling_mod != probed_mod) {
                         if (unlikely(!try_module_get(probed_mod))) {
                                 preempt_enable();
                                 return -EINVAL;
                         }
-                        p->mod_refcounted = 1;
                 } else
                         probed_mod = NULL;
         }
@@ -687,8 +709,9 @@ static int __kprobes __register_kprobe(struct kprobe *p,
 out:
         mutex_unlock(&kprobe_mutex);
 
-        if (ret && probed_mod)
+        if (probed_mod)
                 module_put(probed_mod);
+
         return ret;
 }
 
@@ -716,16 +739,16 @@ valid_p:
              list_is_singular(&old_p->list))) {
                 /*
                  * Only probe on the hash list. Disarm only if kprobes are
-                 * enabled - otherwise, the breakpoint would already have
-                 * been removed. We save on flushing icache.
+                 * enabled and not gone - otherwise, the breakpoint would
+                 * already have been removed. We save on flushing icache.
                  */
-                if (kprobe_enabled)
+                if (kprobe_enabled && !kprobe_gone(old_p))
                         arch_disarm_kprobe(p);
                 hlist_del_rcu(&old_p->hlist);
         } else {
-                if (p->break_handler)
+                if (p->break_handler && !kprobe_gone(p))
                         old_p->break_handler = NULL;
-                if (p->post_handler) {
+                if (p->post_handler && !kprobe_gone(p)) {
                         list_for_each_entry_rcu(list_p, &old_p->list, list) {
                                 if ((list_p != p) && (list_p->post_handler))
                                         goto noclean;
@@ -740,27 +763,16 @@ noclean:
 
 static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
 {
-        struct module *mod;
         struct kprobe *old_p;
 
-        if (p->mod_refcounted) {
-                /*
-                 * Since we've already incremented refcount,
-                 * we don't need to disable preemption.
-                 */
-                mod = module_text_address((unsigned long)p->addr);
-                if (mod)
-                        module_put(mod);
-        }
-
-        if (list_empty(&p->list) || list_is_singular(&p->list)) {
-                if (!list_empty(&p->list)) {
-                        /* "p" is the last child of an aggr_kprobe */
-                        old_p = list_entry(p->list.next, struct kprobe, list);
-                        list_del(&p->list);
-                        kfree(old_p);
-                }
+        if (list_empty(&p->list))
                 arch_remove_kprobe(p);
+        else if (list_is_singular(&p->list)) {
+                /* "p" is the last child of an aggr_kprobe */
+                old_p = list_entry(p->list.next, struct kprobe, list);
+                list_del(&p->list);
+                arch_remove_kprobe(old_p);
+                kfree(old_p);
         }
 }
 
@@ -1074,6 +1086,67 @@ static int __kprobes pre_handler_kretprobe(struct kprobe *p,
 
 #endif /* CONFIG_KRETPROBES */
 
+/* Set the kprobe gone and remove its instruction buffer. */
+static void __kprobes kill_kprobe(struct kprobe *p)
+{
+        struct kprobe *kp;
+        p->flags |= KPROBE_FLAG_GONE;
+        if (p->pre_handler == aggr_pre_handler) {
+                /*
+                 * If this is an aggr_kprobe, we have to list all the
+                 * chained probes and mark them GONE.
+                 */
+                list_for_each_entry_rcu(kp, &p->list, list)
+                        kp->flags |= KPROBE_FLAG_GONE;
+                p->post_handler = NULL;
+                p->break_handler = NULL;
+        }
+        /*
+         * Here, we can remove insn_slot safely, because no thread calls
+         * the original probed function (which will be freed soon) any more.
+         */
+        arch_remove_kprobe(p);
+}
+
+/* Module notifier call back, checking kprobes on the module */
+static int __kprobes kprobes_module_callback(struct notifier_block *nb,
+                                             unsigned long val, void *data)
+{
+        struct module *mod = data;
+        struct hlist_head *head;
+        struct hlist_node *node;
+        struct kprobe *p;
+        unsigned int i;
+
+        if (val != MODULE_STATE_GOING)
+                return NOTIFY_DONE;
+
+        /*
+         * module .text section will be freed. We need to
+         * disable kprobes which have been inserted in the section.
+         */
+        mutex_lock(&kprobe_mutex);
+        for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
+                head = &kprobe_table[i];
+                hlist_for_each_entry_rcu(p, node, head, hlist)
+                        if (within_module_core((unsigned long)p->addr, mod)) {
+                                /*
+                                 * The vaddr this probe is installed will soon
+                                 * be vfreed buy not synced to disk. Hence,
+                                 * disarming the breakpoint isn't needed.
+                                 */
+                                kill_kprobe(p);
+                        }
+        }
+        mutex_unlock(&kprobe_mutex);
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block kprobe_module_nb = {
+        .notifier_call = kprobes_module_callback,
+        .priority = 0
+};
+
 static int __init init_kprobes(void)
 {
         int i, err = 0;
@@ -1130,6 +1203,9 @@ static int __init init_kprobes(void)
         err = arch_init_kprobes();
         if (!err)
                 err = register_die_notifier(&kprobe_exceptions_nb);
+        if (!err)
+                err = register_module_notifier(&kprobe_module_nb);
+
         kprobes_initialized = (err == 0);
 
         if (!err)
@@ -1150,10 +1226,12 @@ static void __kprobes report_probe(struct seq_file *pi, struct kprobe *p,
         else
                 kprobe_type = "k";
         if (sym)
-                seq_printf(pi, "%p  %s  %s+0x%x  %s\n", p->addr, kprobe_type,
-                        sym, offset, (modname ? modname : " "));
+                seq_printf(pi, "%p  %s  %s+0x%x  %s %s\n", p->addr, kprobe_type,
+                        sym, offset, (modname ? modname : " "),
+                        (kprobe_gone(p) ? "[GONE]" : ""));
         else
-                seq_printf(pi, "%p  %s  %p\n", p->addr, kprobe_type, p->addr);
+                seq_printf(pi, "%p  %s  %p %s\n", p->addr, kprobe_type, p->addr,
+                        (kprobe_gone(p) ? "[GONE]" : ""));
 }
 
 static void __kprobes *kprobe_seq_start(struct seq_file *f, loff_t *pos)
@@ -1234,7 +1312,8 @@ static void __kprobes enable_all_kprobes(void)
         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                 head = &kprobe_table[i];
                 hlist_for_each_entry_rcu(p, node, head, hlist)
-                        arch_arm_kprobe(p);
+                        if (!kprobe_gone(p))
+                                arch_arm_kprobe(p);
         }
 
         kprobe_enabled = true;
@@ -1263,7 +1342,7 @@ static void __kprobes disable_all_kprobes(void)
         for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
                 head = &kprobe_table[i];
                 hlist_for_each_entry_rcu(p, node, head, hlist) {
-                        if (!arch_trampoline_kprobe(p))
+                        if (!arch_trampoline_kprobe(p) && !kprobe_gone(p))
                                 arch_disarm_kprobe(p);
                 }
         }