Patch "livepatch: add module locking around kallsyms calls" has been added to the 4.1-stable tree

This is a note to let you know that I've just added the patch titled

livepatch: add module locking around kallsyms calls

to the 4.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
livepatch-add-module-locking-around-kallsyms-calls.patch
and it can be found in the queue-4.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Miroslav Benes <[email protected]>
Date: Mon, 1 Jun 2015 17:48:37 +0200
Subject: livepatch: add module locking around kallsyms calls

From: Miroslav Benes <[email protected]>

commit 9a1bd63cdae4b623494c4ebaf723a91c35ec49fb upstream.

The list of loaded modules is walked through in module_kallsyms_on_each_symbol (called by kallsyms_on_each_symbol). The module_mutex lock should be acquired to prevent potential corruptions in the list.

This was uncovered with new lockdep asserts in module code introduced by the commit 0be964be0d45 ("module: Sanitize RCU usage and locking") in recent next- trees.

---
 kernel/livepatch/core.c |   18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

@@ -179,7 +179,9 @@ static int klp_find_object_symbol(const
 		.count = 0
 	};
 
+	mutex_lock(&module_mutex);
 	kallsyms_on_each_symbol(klp_find_callback, &args);
+	mutex_unlock(&module_mutex);
 
 	if (args.count == 0)
 		pr_err("symbol '%s' not found in symbol table\n", name);

@@ -219,13 +221,19 @@ static int klp_verify_vmlinux_symbol(con
 		.name = name,
 		.addr = addr,
 	};
+	int ret;
 
-	if (kallsyms_on_each_symbol(klp_verify_callback, &args))
-		return 0;
+	mutex_lock(&module_mutex);
+	ret = kallsyms_on_each_symbol(klp_verify_callback, &args);
+	mutex_unlock(&module_mutex);
+
+	if (!ret) {
+		pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
+			name, addr);
+		return -EINVAL;
+	}
 
-	pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
-		name, addr);
-	return -EINVAL;
+	return 0;
 }
 
 static int klp_find_verify_func_addr(struct klp_object *obj,

Patches currently in stable-queue which might be from [email protected] are

queue-4.1/livepatch-add-module-locking-around-kallsyms-calls.patch