From 0a9c63fae7df086ff5e107273c3cce8642430974 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Fri, 15 Jun 2012 13:02:58 -0400 Subject: [PATCH] NFSv4.1: Fix a race in set_pnfs_layoutdriver The call to try_module_get() dereferences ld_type outside the spin locks, which means that it may be pointing to garbage if a module unload was in progress. Signed-off-by: Trond Myklebust --- fs/nfs/pnfs.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index bdf7e52943c8..bbc49caa7a82 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -70,6 +70,10 @@ find_pnfs_driver(u32 id) spin_lock(&pnfs_spinlock); local = find_pnfs_driver_locked(id); + if (local != NULL && !try_module_get(local->owner)) { + dprintk("%s: Could not grab reference on module\n", __func__); + local = NULL; + } spin_unlock(&pnfs_spinlock); return local; } @@ -118,10 +122,6 @@ set_pnfs_layoutdriver(struct nfs_server *server, const struct nfs_fh *mntfh, goto out_no_driver; } } - if (!try_module_get(ld_type->owner)) { - dprintk("%s: Could not grab reference on module\n", __func__); - goto out_no_driver; - } server->pnfs_curr_ld = ld_type; if (ld_type->set_layoutdriver && ld_type->set_layoutdriver(server, mntfh)) { -- 2.30.2