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Commit 30f3deee authored by NeilBrown's avatar NeilBrown Committed by Linus Torvalds
Browse files

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: default avatarNeil Brown <neilb@suse.de>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 94256dd6

net/sunrpc/svcauth_unix.c

+16 −5
Original line number Diff line number Diff line
@@ -383,7 +383,10 @@ void svcauth_unix_purge(void) 
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 @@ ip_map_cached_get(struct svc_rqst *rqstp) 
			 * 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 @@ ip_map_cached_put(struct svc_rqst *rqstp, struct ip_map *ipm) 
{

	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);

}