wifi: iwlwifi: dvm: Fix memcpy: detected field-spanning write backtrace

[ Upstream commit ef167996

 ]

A received TKIP key may be up to 32 bytes because it may contain
MIC rx/tx keys too. These are not used by iwl and copying these
over overflows the iwl_keyinfo.key field.

Add a check to not copy more data to iwl_keyinfo.key then will fit.

This fixes backtraces like this one:

 memcpy: detected field-spanning write (size 32) of single field "sta_cmd.key.key" at drivers/net/wireless/intel/iwlwifi/dvm/sta.c:1103 (size 16)
 WARNING: CPU: 1 PID: 946 at drivers/net/wireless/intel/iwlwifi/dvm/sta.c:1103 iwlagn_send_sta_key+0x375/0x390 [iwldvm]
 <snip>
 Hardware name: Dell Inc. Latitude E6430/0H3MT5, BIOS A21 05/08/2017
 RIP: 0010:iwlagn_send_sta_key+0x375/0x390 [iwldvm]
 <snip>
 Call Trace:
  <TASK>
  iwl_set_dynamic_key+0x1f0/0x220 [iwldvm]
  iwlagn_mac_set_key+0x1e4/0x280 [iwldvm]
  drv_set_key+0xa4/0x1b0 [mac80211]
  ieee80211_key_enable_hw_accel+0xa8/0x2d0 [mac80211]
  ieee80211_key_replace+0x22d/0x8e0 [mac80211]
 <snip>

Link: https://www.alionet.org/index.php?topic=1469.0
Link: https://lore.kernel.org/linux-wireless/20230218191056.never.374-kees@kernel.org/
Link: https://lore.kernel.org/linux-wireless/68760035-7f75-1b23-e355-bfb758a87d83@redhat.com/
Cc: Kees Cook <keescook@chromium.org>
Suggested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>