On Mar 30, 2023, at 2:49 PM, Jeff Layton [off-list ref] wrote:

On Thu, 2023-03-30 at 18:31 +0000, Chuck Lever III wrote:

quoted

Hi Jeff-

quoted

On Mar 30, 2023, at 2:24 PM, Jeff Layton [off-list ref] wrote:

While the unix_gid object is rcu-freed, the group_info list that it
contains is not. Ensure that we only put the group list reference once
we are really freeing the unix_gid object.

Reported-by: Zhi Li <redacted>

Should we also add

Fixes: fd5d2f78261b ("SUNRPC: Make server side AUTH_UNIX use lockless lookups") ?

Sure. That does look like when that particular bug crept in.

quoted

quoted

Link: https://bugzilla.redhat.com/show_bug.cgi?id=2183056

This bug isn't publicly accessible, fwiw.

Thanks. It should be now.

OK, applied to nfsd-fixes!

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Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
net/sunrpc/svcauth_unix.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index 50e2eb579194..4485088ce27b 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c

@@ -416,14 +416,23 @@ static int unix_gid_hash(kuid_t uid)

	return hash_long(from_kuid(&init_user_ns, uid), GID_HASHBITS);
}

-static void unix_gid_put(struct kref *kref)
+static void unix_gid_free(struct rcu_head *rcu)
{
-	struct cache_head *item = container_of(kref, struct cache_head, ref);
-	struct unix_gid *ug = container_of(item, struct unix_gid, h);
+	struct unix_gid *ug = container_of(rcu, struct unix_gid, rcu);
+	struct cache_head *item = &ug->h;
+
	if (test_bit(CACHE_VALID, &item->flags) &&
	    !test_bit(CACHE_NEGATIVE, &item->flags))
		put_group_info(ug->gi);
-	kfree_rcu(ug, rcu);
+	kfree(ug);
+}
+
+static void unix_gid_put(struct kref *kref)
+{
+	struct cache_head *item = container_of(kref, struct cache_head, ref);
+	struct unix_gid *ug = container_of(item, struct unix_gid, h);
+
+	call_rcu(&ug->rcu, unix_gid_free);
}

static int unix_gid_match(struct cache_head *corig, struct cache_head *cnew)
-- 
2.39.2

--
Chuck Lever

-- 
Jeff Layton [off-list ref]

--
Chuck Lever