6.11-stable review patch. If anyone has any objections, please let me know.
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From: Christian Brauner brauner@kernel.org
commit 229fd15908fe1f99b1de4cde3326e62d1e892611 upstream.
When copying a namespace we won't have added the new copy into the namespace rbtree until after the copy succeeded. Calling free_mnt_ns() will try to remove the copy from the rbtree which is invalid. Simply free the namespace skeleton directly.
Link: https://lore.kernel.org/r/20241016-adapter-seilwinde-83c508a7bde1@brauner Fixes: 1901c92497bd ("fs: keep an index of current mount namespaces") Tested-by: Brad Spengler spender@grsecurity.net Cc: stable@vger.kernel.org # v6.11+ Reported-by: Brad Spengler spender@grsecurity.net Suggested-by: Brad Spengler spender@grsecurity.net Signed-off-by: Christian Brauner brauner@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/namespace.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/fs/namespace.c +++ b/fs/namespace.c @@ -3917,7 +3917,9 @@ struct mnt_namespace *copy_mnt_ns(unsign new = copy_tree(old, old->mnt.mnt_root, copy_flags); if (IS_ERR(new)) { namespace_unlock(); - free_mnt_ns(new_ns); + ns_free_inum(&new_ns->ns); + dec_mnt_namespaces(new_ns->ucounts); + mnt_ns_release(new_ns); return ERR_CAST(new); } if (user_ns != ns->user_ns) {