Re: [RFC PATCH v3] audit: use proper refcount locking on audit_sock
On Tue, Dec 13, 2016 at 10:03 AM, Richard Guy Briggs <rgb(a)redhat.com> wrote:
Resetting audit_sock appears to be racy.
audit_sock was being copied and dereferenced without using a refcount on
the source sock.
Bump the refcount on the underlying sock when we store a refrence in
audit_sock and release it when we reset audit_sock. audit_sock
modification needs the audit_cmd_mutex.
See: https://lkml.org/lkml/2016/11/26/232
Thanks to Eric Dumazet <edumazet(a)google.com> and Cong Wang
<xiyou.wangcong(a)gmail.com> on ideas how to fix it.
Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com>
---
There has been a lot of change in the audit code that is about to go
upstream to address audit queue issues. This patch is based on the
source tree: git://git.infradead.org/users/pcmoore/audit#next
---
kernel/audit.c | 28 +++++++++++++++++++++++-----
1 files changed, 23 insertions(+), 5 deletions(-)
This looks more reasonable. I still wonder about synchronization
between threads changing the audit_* connection variables and the
kauditd_thread, but I guess we can treat that as another issue; this
patch fixes a bug and is worth merging now.
I'm building a test kernel right now, assuming nothing blows up I'll
push this patch with the rest of the audit patches tomorrow; if
something bad happens, this is going to miss the first audit pull
request.
diff --git a/kernel/audit.c b/kernel/audit.c
index f20eee0..3bb4126 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -446,14 +446,19 @@ static void kauditd_retry_skb(struct sk_buff *skb)
* Description:
* Break the auditd/kauditd connection and move all the records in the retry
* queue into the hold queue in case auditd reconnects.
+ * The audit_cmd_mutex must be held when calling this function.
*/
Don't resend, but in the future please start comments like this on the
previous line.