2005-05-19 23:22:20

by Al Viro

[permalink] [raw]
Subject: [CFR][PATCH] namei fixes (13/19)

(13/19)

In open_namei() exit_dput: we have mntput() done in the wrong order -
if nd->mnt != path.mnt we end up doing
mntput(nd->mnt);
nd->mnt = path.mnt;
dput(nd->dentry);
mntput(nd->mnt);
which drops nd->dentry too late. Fixed by having path.mnt go first.
That allows to switch O_NOFOLLOW under if (__follow_mount(...)) back
to exit_dput, while we are at it.

Fix for early-mntput() race + equivalent transformation.

Signed-off-by: Al Viro <[email protected]>
----
diff -urN RC12-rc4-12/fs/namei.c RC12-rc4-13/fs/namei.c
--- RC12-rc4-12/fs/namei.c 2005-05-19 16:39:41.456242973 -0400
+++ RC12-rc4-13/fs/namei.c 2005-05-19 16:39:42.545026018 -0400
@@ -1501,11 +1501,8 @@

if (__follow_mount(&path)) {
error = -ELOOP;
- if (flag & O_NOFOLLOW) {
- dput(path.dentry);
- mntput(path.mnt);
- goto exit;
- }
+ if (flag & O_NOFOLLOW)
+ goto exit_dput;
}
error = -ENOENT;
if (!path.dentry->d_inode)
@@ -1530,8 +1527,7 @@
exit_dput:
dput(path.dentry);
if (nd->mnt != path.mnt)
- mntput(nd->mnt);
- nd->mnt = path.mnt;
+ mntput(path.mnt);
exit:
path_release(nd);
return error;