3 files changed, 109 insertions, 51 deletions

diff --git a/kernel/module/internal.h b/kernel/module/internal.h
index dc7b0160c480..c8b7b4dcf782 100644
--- a/kernel/module/internal.h
+++ b/kernel/module/internal.h
@@ -32,6 +32,18 @@
 /* Maximum number of characters written by module_flags() */
 #define MODULE_FLAGS_BUF_SIZE (TAINT_FLAGS_COUNT + 4)
 
+struct kernel_symbol {
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+	int value_offset;
+	int name_offset;
+	int namespace_offset;
+#else
+	unsigned long value;
+	const char *name;
+	const char *namespace;
+#endif
+};
+
 extern struct mutex module_mutex;
 extern struct list_head modules;
 
diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c
index c550d7d45f2f..ef73ae7c8909 100644
--- a/kernel/module/kallsyms.c
+++ b/kernel/module/kallsyms.c
@@ -381,34 +381,6 @@ out:
 	return -ERANGE;
 }
 
-int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size,
-			       unsigned long *offset, char *modname, char *name)
-{
-	struct module *mod;
-
-	preempt_disable();
-	list_for_each_entry_rcu(mod, &modules, list) {
-		if (mod->state == MODULE_STATE_UNFORMED)
-			continue;
-		if (within_module(addr, mod)) {
-			const char *sym;
-
-			sym = find_kallsyms_symbol(mod, addr, size, offset);
-			if (!sym)
-				goto out;
-			if (modname)
-				strscpy(modname, mod->name, MODULE_NAME_LEN);
-			if (name)
-				strscpy(name, sym, KSYM_NAME_LEN);
-			preempt_enable();
-			return 0;
-		}
-	}
-out:
-	preempt_enable();
-	return -ERANGE;
-}
-
 int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
 		       char *name, char *module_name, int *exported)
 {
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 4e2cf784cf8c..834de86ebe35 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -820,10 +820,8 @@ static struct module_attribute modinfo_refcnt =
 void __module_get(struct module *module)
 {
 	if (module) {
-		preempt_disable();
 		atomic_inc(&module->refcnt);
 		trace_module_get(module, _RET_IP_);
-		preempt_enable();
 	}
 }
 EXPORT_SYMBOL(__module_get);
@@ -833,15 +831,12 @@ bool try_module_get(struct module *module)
 	bool ret = true;
 
 	if (module) {
-		preempt_disable();
 		/* Note: here, we can fail to get a reference */
 		if (likely(module_is_live(module) &&
 			   atomic_inc_not_zero(&module->refcnt) != 0))
 			trace_module_get(module, _RET_IP_);
 		else
 			ret = false;
-
-		preempt_enable();
 	}
 	return ret;
 }
@@ -852,11 +847,9 @@ void module_put(struct module *module)
 	int ret;
 
 	if (module) {
-		preempt_disable();
 		ret = atomic_dec_if_positive(&module->refcnt);
 		WARN_ON(ret < 0);	/* Failed to put refcount */
 		trace_module_put(module, _RET_IP_);
-		preempt_enable();
 	}
 }
 EXPORT_SYMBOL(module_put);
@@ -3057,26 +3050,83 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
 	return load_module(&info, uargs, 0);
 }
 
-SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
+struct idempotent {
+	const void *cookie;
+	struct hlist_node entry;
+	struct completion complete;
+	int ret;
+};
+
+#define IDEM_HASH_BITS 8
+static struct hlist_head idem_hash[1 << IDEM_HASH_BITS];
+static DEFINE_SPINLOCK(idem_lock);
+
+static bool idempotent(struct idempotent *u, const void *cookie)
+{
+	int hash = hash_ptr(cookie, IDEM_HASH_BITS);
+	struct hlist_head *head = idem_hash + hash;
+	struct idempotent *existing;
+	bool first;
+
+	u->ret = 0;
+	u->cookie = cookie;
+	init_completion(&u->complete);
+
+	spin_lock(&idem_lock);
+	first = true;
+	hlist_for_each_entry(existing, head, entry) {
+		if (existing->cookie != cookie)
+			continue;
+		first = false;
+		break;
+	}
+	hlist_add_head(&u->entry, idem_hash + hash);
+	spin_unlock(&idem_lock);
+
+	return !first;
+}
+
+/*
+ * We were the first one with 'cookie' on the list, and we ended
+ * up completing the operation. We now need to walk the list,
+ * remove everybody - which includes ourselves - fill in the return
+ * value, and then complete the operation.
+ */
+static void idempotent_complete(struct idempotent *u, int ret)
+{
+	const void *cookie = u->cookie;
+	int hash = hash_ptr(cookie, IDEM_HASH_BITS);
+	struct hlist_head *head = idem_hash + hash;
+	struct hlist_node *next;
+	struct idempotent *pos;
+
+	spin_lock(&idem_lock);
+	hlist_for_each_entry_safe(pos, next, head, entry) {
+		if (pos->cookie != cookie)
+			continue;
+		hlist_del(&pos->entry);
+		pos->ret = ret;
+		complete(&pos->complete);
+	}
+	spin_unlock(&idem_lock);
+}
+
+static int init_module_from_file(struct file *f, const char __user * uargs, int flags)
 {
+	struct idempotent idem;
 	struct load_info info = { };
 	void *buf = NULL;
-	int len;
-	int err;
-
-	err = may_init_module();
-	if (err)
-		return err;
+	int len, ret;
 
-	pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags);
+	if (!f || !(f->f_mode & FMODE_READ))
+		return -EBADF;
 
-	if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS
-		      |MODULE_INIT_IGNORE_VERMAGIC
-		      |MODULE_INIT_COMPRESSED_FILE))
-		return -EINVAL;
+	if (idempotent(&idem, file_inode(f))) {
+		wait_for_completion(&idem.complete);
+		return idem.ret;
+	}
 
-	len = kernel_read_file_from_fd(fd, 0, &buf, INT_MAX, NULL,
-				       READING_MODULE);
+	len = kernel_read_file(f, 0, &buf, INT_MAX, NULL, READING_MODULE);
 	if (len < 0) {
 		mod_stat_inc(&failed_kreads);
 		mod_stat_add_long(len, &invalid_kread_bytes);
@@ -3084,7 +3134,7 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
 	}
 
 	if (flags & MODULE_INIT_COMPRESSED_FILE) {
-		err = module_decompress(&info, buf, len);
+		int err = module_decompress(&info, buf, len);
 		vfree(buf); /* compressed data is no longer needed */
 		if (err) {
 			mod_stat_inc(&failed_decompress);
@@ -3096,7 +3146,31 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
 		info.len = len;
 	}
 
-	return load_module(&info, uargs, flags);
+	ret = load_module(&info, uargs, flags);
+	idempotent_complete(&idem, ret);
+	return ret;
+}
+
+SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
+{
+	int err;
+	struct fd f;
+
+	err = may_init_module();
+	if (err)
+		return err;
+
+	pr_debug("finit_module: fd=%d, uargs=%p, flags=%i\n", fd, uargs, flags);
+
+	if (flags & ~(MODULE_INIT_IGNORE_MODVERSIONS
+		      |MODULE_INIT_IGNORE_VERMAGIC
+		      |MODULE_INIT_COMPRESSED_FILE))
+		return -EINVAL;
+
+	f = fdget(fd);
+	err = init_module_from_file(f.file, uargs, flags);
+	fdput(f);
+	return err;
 }
 
 /* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */