knfsd: use a spinlock to protect sk_info_authunix
sk_info_authunix is not being protected properly so the object that it
points to can be cache_put twice, leading to corruption.
We borrow svsk->sk_defer_lock to provide the protection. We should
probably rename that lock to have a more generic name - later.
Thanks to Gabriel for reporting this.
Cc: Greg Banks <gnb@melbourne.sgi.com>
Cc: Gabriel Barazer <gabriel@oxeva.fr>
Signed-off-by: Neil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index 9bae409..2bd23ea 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -383,7 +383,10 @@
static inline struct ip_map *
ip_map_cached_get(struct svc_rqst *rqstp)
{
- struct ip_map *ipm = rqstp->rq_sock->sk_info_authunix;
+ struct ip_map *ipm;
+ struct svc_sock *svsk = rqstp->rq_sock;
+ spin_lock_bh(&svsk->sk_defer_lock);
+ ipm = svsk->sk_info_authunix;
if (ipm != NULL) {
if (!cache_valid(&ipm->h)) {
/*
@@ -391,12 +394,14 @@
* remembered, e.g. by a second mount from the
* same IP address.
*/
- rqstp->rq_sock->sk_info_authunix = NULL;
+ svsk->sk_info_authunix = NULL;
+ spin_unlock_bh(&svsk->sk_defer_lock);
cache_put(&ipm->h, &ip_map_cache);
return NULL;
}
cache_get(&ipm->h);
}
+ spin_unlock_bh(&svsk->sk_defer_lock);
return ipm;
}
@@ -405,9 +410,15 @@
{
struct svc_sock *svsk = rqstp->rq_sock;
- if (svsk->sk_sock->type == SOCK_STREAM && svsk->sk_info_authunix == NULL)
- svsk->sk_info_authunix = ipm; /* newly cached, keep the reference */
- else
+ spin_lock_bh(&svsk->sk_defer_lock);
+ if (svsk->sk_sock->type == SOCK_STREAM &&
+ svsk->sk_info_authunix == NULL) {
+ /* newly cached, keep the reference */
+ svsk->sk_info_authunix = ipm;
+ ipm = NULL;
+ }
+ spin_unlock_bh(&svsk->sk_defer_lock);
+ if (ipm)
cache_put(&ipm->h, &ip_map_cache);
}