livepatch: add module locking around kallsyms calls
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.
Signed-off-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/kernel/livepatch/core.c b/kernel/livepatch/core.c
index 284e269..9ec5557 100644
--- a/kernel/livepatch/core.c
+++ b/kernel/livepatch/core.c
@@ -179,7 +179,9 @@
.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 @@
.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);
- pr_err("symbol '%s' not found at specified address 0x%016lx, kernel mismatch?\n",
- name, addr);
- return -EINVAL;
+ if (!ret) {
+ 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,
