| From 9a1bd63cdae4b623494c4ebaf723a91c35ec49fb Mon Sep 17 00:00:00 2001 |
| From: Miroslav Benes <mbenes@suse.cz> |
| Date: Mon, 1 Jun 2015 17:48:37 +0200 |
| Subject: livepatch: add module locking around kallsyms calls |
| |
| From: Miroslav Benes <mbenes@suse.cz> |
| |
| 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. |
| |
| Signed-off-by: Miroslav Benes <mbenes@suse.cz> |
| Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> |
| Signed-off-by: Jiri Kosina <jkosina@suse.cz> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| kernel/livepatch/core.c | 18 +++++++++++++----- |
| 1 file changed, 13 insertions(+), 5 deletions(-) |
| |
| --- a/kernel/livepatch/core.c |
| +++ b/kernel/livepatch/core.c |
| @@ -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, |