From db4aad209bc9aefd91f0a9aeb9e37364088b39ad Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Fri, 17 Jan 2014 09:58:25 -0500 Subject: kernfs: associate a new kernfs_node with its parent on creation Once created, a kernfs_node is always destroyed by kernfs_put(). Since ba7443bc656e ("sysfs, kernfs: implement kernfs_create/destroy_root()"), kernfs_put() depends on kernfs_root() to locate the ino_ida. kernfs_root() in turn depends on kernfs_node->parent being set for !dir nodes. This means that kernfs_put() of a !dir node requires its ->parent to be initialized. This leads to oops when a newly created !dir node is destroyed without going through kernfs_add_one() or after failing kernfs_add_one() before ->parent is set. kernfs_root() invoked from kernfs_put() will try to dereference NULL parent. Fix it by moving parent association to kernfs_new_node() from kernfs_add_one(). kernfs_new_node() now takes @parent instead of @root and determines the root from the parent and also sets the new node's parent properly. @parent parameter is removed from kernfs_add_one(). As there's no parent when creating the root node, __kernfs_new_node() which takes @root as before and doesn't set the parent is used in that case. This ensures that a kernfs_node in any stage in its life has its parent associated and thus can be put. Signed-off-by: Tejun Heo Signed-off-by: Greg Kroah-Hartman --- fs/kernfs/symlink.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'fs/kernfs/symlink.c') diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c index a03e26036ef9..4d457055acb9 100644 --- a/fs/kernfs/symlink.c +++ b/fs/kernfs/symlink.c @@ -30,8 +30,7 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, struct kernfs_addrm_cxt acxt; int error; - kn = kernfs_new_node(kernfs_root(parent), name, S_IFLNK|S_IRWXUGO, - KERNFS_LINK); + kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, KERNFS_LINK); if (!kn) return ERR_PTR(-ENOMEM); @@ -41,7 +40,7 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent, kernfs_get(target); /* ref owned by symlink */ kernfs_addrm_start(&acxt); - error = kernfs_add_one(&acxt, kn, parent); + error = kernfs_add_one(&acxt, kn); kernfs_addrm_finish(&acxt); if (!error) -- cgit v1.2.3