Re: [PATCH] wifi: iwlwifi: dvm: Fix memcpy: detected field-spanning write backtrace

[Kees Cook <keescook@chromium.org>]

On Tue, Apr 18, 2023 at 03:25:46PM +0200, Hans de Goede wrote:
> 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>

Thanks for chasing this down -- I hadn't had time to come back around to
it.

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook