6.12-stable review patch. If anyone has any objections, please let me know.
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From: Al Viro viro@zeniv.linux.org.uk
commit 1f282cdc1d219c4a557f7009e81bc792820d9d9a upstream.
may_decode_fh() is calling has_locked_children() while holding no locks. That's an oopsable race...
The rest of the callers are safe since they are holding namespace_sem and are guaranteed a positive refcount on the mount in question.
Rename the current has_locked_children() to __has_locked_children(), make it static and switch the fs/namespace.c users to it.
Make has_locked_children() a wrapper for __has_locked_children(), calling the latter under read_seqlock_excl(&mount_lock).
Reviewed-by: Christian Brauner brauner@kernel.org Reviewed-by: Jeff Layton jlayton@kernel.org Fixes: 620c266f3949 ("fhandle: relax open_by_handle_at() permission checks") Signed-off-by: Al Viro viro@zeniv.linux.org.uk [ Harshit: Resolved conflicts due to missing commit: db04662e2f4f ("fs: allow detached mounts in clone_private_mount()") in linux-6.12.y ] Signed-off-by: Harshit Mogalapalli harshit.m.mogalapalli@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/namespace.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)
--- a/fs/namespace.c +++ b/fs/namespace.c @@ -2227,7 +2227,7 @@ void drop_collected_mounts(struct vfsmou namespace_unlock(); }
-bool has_locked_children(struct mount *mnt, struct dentry *dentry) +static bool __has_locked_children(struct mount *mnt, struct dentry *dentry) { struct mount *child;
@@ -2241,6 +2241,16 @@ bool has_locked_children(struct mount *m return false; }
+bool has_locked_children(struct mount *mnt, struct dentry *dentry) +{ + bool res; + + read_seqlock_excl(&mount_lock); + res = __has_locked_children(mnt, dentry); + read_sequnlock_excl(&mount_lock); + return res; +} + /** * clone_private_mount - create a private clone of a path * @path: path to clone @@ -2268,7 +2278,7 @@ struct vfsmount *clone_private_mount(con return ERR_PTR(-EPERM); }
- if (has_locked_children(old_mnt, path->dentry)) + if (__has_locked_children(old_mnt, path->dentry)) goto invalid;
new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); @@ -2762,7 +2772,7 @@ static struct mount *__do_loopback(struc if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) return mnt;
- if (!recurse && has_locked_children(old, old_path->dentry)) + if (!recurse && __has_locked_children(old, old_path->dentry)) return mnt;
if (recurse) @@ -3152,7 +3162,7 @@ static int do_set_group(struct path *fro goto out;
/* From mount should not have locked children in place of To's root */ - if (has_locked_children(from, to->mnt.mnt_root)) + if (__has_locked_children(from, to->mnt.mnt_root)) goto out;
/* Setting sharing groups is only allowed on private mounts */