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authorAl Viro <viro@zeniv.linux.org.uk>2019-11-08 22:08:29 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2019-11-10 11:56:05 -0500
commita2ece088882666e1dc7113744ac912eb161e3f87 (patch)
tree95f1b04119e74feef66d679c49df9f010acead29 /fs/exportfs
parent630faf81b3e61bcc90dc6d8b497800657d2752a5 (diff)
downloadlwn-a2ece088882666e1dc7113744ac912eb161e3f87.tar.gz
lwn-a2ece088882666e1dc7113744ac912eb161e3f87.zip
exportfs_decode_fh(): negative pinned may become positive without the parent locked
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/exportfs')
-rw-r--r--fs/exportfs/expfs.c31
1 files changed, 19 insertions, 12 deletions
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 09bc68708d28..2dd55b172d57 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -519,26 +519,33 @@ struct dentry *exportfs_decode_fh(struct vfsmount *mnt, struct fid *fid,
* inode is actually connected to the parent.
*/
err = exportfs_get_name(mnt, target_dir, nbuf, result);
- if (!err) {
- inode_lock(target_dir->d_inode);
- nresult = lookup_one_len(nbuf, target_dir,
- strlen(nbuf));
- inode_unlock(target_dir->d_inode);
- if (!IS_ERR(nresult)) {
- if (nresult->d_inode) {
- dput(result);
- result = nresult;
- } else
- dput(nresult);
- }
+ if (err) {
+ dput(target_dir);
+ goto err_result;
}
+ inode_lock(target_dir->d_inode);
+ nresult = lookup_one_len(nbuf, target_dir, strlen(nbuf));
+ if (!IS_ERR(nresult)) {
+ if (unlikely(nresult->d_inode != result->d_inode)) {
+ dput(nresult);
+ nresult = ERR_PTR(-ESTALE);
+ }
+ }
+ inode_unlock(target_dir->d_inode);
/*
* At this point we are done with the parent, but it's pinned
* by the child dentry anyway.
*/
dput(target_dir);
+ if (IS_ERR(nresult)) {
+ err = PTR_ERR(nresult);
+ goto err_result;
+ }
+ dput(result);
+ result = nresult;
+
/*
* And finally make sure the dentry is actually acceptable
* to NFSD.