kprobes: support probing module __init function

Allow kprobes to probe module __init routines.  When __init functions are
freed, kprobes which probe those functions are set to "Gone" flag.  These
"Gone" probes are disarmed from the code and never be enabled.

Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 4 deletions

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index ddefb9fae0c8..1b9cbdc0127a 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -677,6 +677,16 @@ int __kprobes register_kprobe(struct kprobe *p)
                         preempt_enable();
                         return -EINVAL;
                 }
+                /*
+                 * If the module freed .init.text, we couldn't insert
+                 * kprobes in there.
+                 */
+                if (within_module_init((unsigned long)p->addr, probed_mod) &&
+                    probed_mod->state != MODULE_STATE_COMING) {
+                        module_put(probed_mod);
+                        preempt_enable();
+                        return -EINVAL;
+                }
         }
         preempt_enable();
 
@@ -1073,19 +1083,24 @@ static int __kprobes kprobes_module_callback(struct notifier_block *nb,
         struct hlist_node *node;
         struct kprobe *p;
         unsigned int i;
+        int checkcore = (val == MODULE_STATE_GOING);
 
-        if (val != MODULE_STATE_GOING)
+        if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
                 return NOTIFY_DONE;
 
         /*
-         * module .text section will be freed. We need to
-         * disable kprobes which have been inserted in the section.
+         * When MODULE_STATE_GOING was notified, both of module .text and
+         * .init.text sections would be freed. When MODULE_STATE_LIVE was
+         * notified, only .init.text section would be freed. We need to
+         * disable kprobes which have been inserted in the sections.
          */
         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)) {
+                        if (within_module_init((unsigned long)p->addr, mod) ||
+                            (checkcore &&
+                             within_module_core((unsigned long)p->addr, mod))) {
                                 /*
                                  * The vaddr this probe is installed will soon
                                  * be vfreed buy not synced to disk. Hence,