wifi: iwlwifi: fix out of bound copy_from_user

wifi: iwlwifi: fix out of bound copy_from_user

[ Upstream commit cb2dfacb197bed0241fbb4f84bd0995a47f4465e ]

The driver copies the userspace buffer into an internal NUL
byte terminated buffer. While doing so, it was reading beyond
the end of the userspace buffer, overwriting its own NUL
termination in the process.

Fix this by only copying the correct number of bytes.

Fixes: 3f244876ef73 ("wifi: iwlwifi: make debugfs entries link specific")
Signed-off-by: Anjaneyulu <pagadala.yesu.anjaneyulu@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Reviewed-by: Benjamin Berg <benjamin.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20231219215605.e4913deb2ad4.Idcf6a7e909ff4b7801cd49c2f691f84a2f68eff9@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>