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| author | Al Viro <viro@zeniv.linux.org.uk> | 2019-11-09 06:08:29 +0300 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2019-11-10 19:56:05 +0300 |
| commit | a2ece088882666e1dc7113744ac912eb161e3f87 (patch) | |
| tree | 95f1b04119e74feef66d679c49df9f010acead29 | |
| parent | 630faf81b3e61bcc90dc6d8b497800657d2752a5 (diff) | |
| download | linux-a2ece088882666e1dc7113744ac912eb161e3f87.tar.xz | |
exportfs_decode_fh(): negative pinned may become positive without the parent locked
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
| -rw-r--r-- | fs/exportfs/expfs.c | 31 |
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. |