Re: v3.19-rc2: crashes during boot (syslog-ng, rpcbind ...)

Paul Moore
2014-12-30T18:46:24Z

On Tuesday, December 30, 2014 09:11:32 AM Paul Moore wrote:
> On Monday, December 29, 2014 09:18:44 PM Toralf Förster wrote:
> > On 12/29/2014 08:41 PM, Paul Moore wrote:
> > > To help verify that I'm heading down the right path, could you share
> > > your audit configuration as well? If that's not possible, can you at
> > > least confirm that you using a few audit directory watches?
> >
> > Well, it is just a victim system for trinity - but I did not configured
> > auditd in a special manner - so it is just the plain default configuration
> > of Gentoo:
>
> Okay, thanks for the information; the file related syscall watches are
> likely what triggered the problem code. Until I've got the fix sorted out,
> removing the syscall watches or just disabling auditd from starting at boot
> should workaround the problem.

I still want to go over the below patch a bit more to check a few things, but
it solves the problem for me and I believe it should solve the problem you are
seeing as well. Can you give it a try and let me know what happens?

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 287b3d3..d834770 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -72,6 +72,8 @@
#include <linux/fs_struct.h>
#include <linux/compat.h>
#include <linux/ctype.h>
+#include <linux/string.h>
+#include <uapi/linux/limits.h>

#include "audit.h"

@@ -1862,7 +1864,7 @@ void __audit_inode(struct filename *name, const struct
dentry *dentry,

list_for_each_entry_reverse(n, &context->names_list, list) {
/* does the name pointer match? */
- if (!n->name || n->name->name != name->name)
+ if (!n->name || strcmp(n->name->name, name->name))
continue;

/* match the correct record type */
@@ -1881,14 +1883,39 @@ out_alloc:
n = audit_alloc_name(context, AUDIT_TYPE_UNKNOWN);
if (!n)
return;
- if (name)
- /* since name is not NULL we know there is already a matching
- * name record, see audit_getname(), so there must be a type
- * mismatch; reuse the string path since the original name
- * record will keep the string valid until we free it in
- * audit_free_names() */
- n->name = name;
+ /* unfortunately, while we may have a path name to record with the
+ * inode, we can't always rely on the string lasting until the end of
+ * the syscall so we need to create our own copy, it may fail due to
+ * memory allocation issues, but we do our best */
+ if (name) {
+ /* we can't use getname_kernel() due to size limits */
+ struct filename *new = __getname();

+ if (unlikely(!new))
+ goto out;
+
+ memset(new, 0, sizeof(*new));
+ if ((strlen(name->name) + 1) <= (PATH_MAX - sizeof(*new))) {
+ char *new_name = (char *)(new) + sizeof(*new);
+ new->name = new_name;
+ new->separate = false;
+ } else {
+ /* this looks odd, but is due to final_putname() */
+ struct filename *new2;
+ new2 = kzalloc(sizeof(*new2), GFP_KERNEL);
+ if (unlikely(!new2)) {
+ __putname(new);
+ goto out;
+ }
+ new2->name = (char *)new;
+ new = new2;
+ new->separate = true;
+ }
+ strcpy((char *)new->name, name->name);
+ new->aname = n;
+ n->name = new;
+ n->name_put = true;
+ }
out:
if (parent) {
n->name_len = n->name ? parent_len(n->name->name) : AUDIT_NAME_FULL;