vsock: ignore empty child namespace mode writes

__vsock_net_mode_string() returns success without updating new_mode when
the transfer length is zero. Its caller then reads the uninitialized enum
and may permanently store a stack-derived value in the write-once child
mode.

Return before calling __vsock_net_mode_string() when *lenp is zero so
that the helper is never invoked with nothing to parse and new_mode is
never read uninitialized. This also prevents an empty write from
locking the current mode.

Fixes: eafb64f40ca4 ("vsock: add netns to vsock core")
Cc: stable@vger.kernel.org
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Signed-off-by: Aldo Ariel Panzardo <qwe.aldo@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260915173050.3176344-1-qwe.aldo@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions