Patch "vfs: open() with O_CREAT should not create inodes with unknown ids" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

vfs: open() with O_CREAT should not create inodes with unknown ids

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
vfs-open-with-o_creat-should-not-create-inodes-with-unknown-ids.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Seth Forshee <[email protected]>
Date: Sat, 7 Oct 2017 22:36:55 +0000
Subject: vfs: open() with O_CREAT should not create inodes with unknown ids

From: Seth Forshee <[email protected]>

[ Upstream commit 1328c727004d432bbdfba0ffa02a166df04c7305 ]

may_create() rejects creation of inodes with ids which lack a mapping into s_user_ns. However for O_CREAT may_o_create() is is used instead. Add a similar check there.

---
 fs/namei.c |    6 ++++++
 1 file changed, 6 insertions(+)

@@ -2971,10 +2971,16 @@ static inline int open_to_namei_flags(in
 
 static int may_o_create(const struct path *dir, struct dentry *dentry, umode_t mode)
 {
+	struct user_namespace *s_user_ns;
 	int error = security_path_mknod(dir, dentry, mode, 0);
 	if (error)
 		return error;
 
+	s_user_ns = dir->dentry->d_sb->s_user_ns;
+	if (!kuid_has_mapping(s_user_ns, current_fsuid()) ||
+	    !kgid_has_mapping(s_user_ns, current_fsgid()))
+		return -EOVERFLOW;
+
 	error = inode_permission(dir->dentry->d_inode, MAY_WRITE | MAY_EXEC);
 	if (error)
 		return error;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/vfs-open-with-o_creat-should-not-create-inodes-with-unknown-ids.patch