| Message ID | 20230418132546.45297-1-hdegoede@redhat.com (mailing list archive) |
|---|---|
| State | Accepted |
| Delegated to: | Johannes Berg |
| Headers | show |
| Series | wifi: iwlwifi: dvm: Fix memcpy: detected field-spanning write backtrace | expand |
On Tue, 2023-04-18 at 15:25 +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. Thanks for doing (and more importantly testing) this :) > - memcpy(sta_cmd.key.key, keyconf->key, keyconf->keylen); > + /* keyconf may contain MIC rx/tx keys which iwl does not use */ > + to_copy = min_t(size_t, sizeof(sta_cmd.key.key), keyconf->keylen); > + memcpy(sta_cmd.key.key, keyconf->key, to_copy); > I'd kind of argue that just hardcoding 16 is fine here, keylen _looks_ variable so the compiler can't optimize it away, but in reality keylen always must be 32 and sizeof() must be always 16 :) But it also really doesn't matter. Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Should we Cc stable on this? johannes
Hi, On 4/18/23 16:43, Johannes Berg wrote: > On Tue, 2023-04-18 at 15:25 +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. > > Thanks for doing (and more importantly testing) this :) > >> - memcpy(sta_cmd.key.key, keyconf->key, keyconf->keylen); >> + /* keyconf may contain MIC rx/tx keys which iwl does not use */ >> + to_copy = min_t(size_t, sizeof(sta_cmd.key.key), keyconf->keylen); >> + memcpy(sta_cmd.key.key, keyconf->key, to_copy); >> > > I'd kind of argue that just hardcoding 16 is fine here, keylen _looks_ > variable so the compiler can't optimize it away, but in reality keylen > always must be 32 and sizeof() must be always 16 :) It is not just the compiler to whom keylen _looks_ variable, so to be safe I went with the min_t() check. I think this also makes the code easier to understand for future readers of the code. > But it also really doesn't matter. > > Reviewed-by: Johannes Berg <johannes@sipsolutions.net> Thanks. > Should we Cc stable on this? Yes I think so. I did not add the tag because some subsystems want that to be left up to the maintainer. Regards, Hans
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>
diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/sta.c b/drivers/net/wireless/intel/iwlwifi/dvm/sta.c index cef43cf80620..8b01ab986cb1 100644 --- a/drivers/net/wireless/intel/iwlwifi/dvm/sta.c +++ b/drivers/net/wireless/intel/iwlwifi/dvm/sta.c @@ -1081,6 +1081,7 @@ static int iwlagn_send_sta_key(struct iwl_priv *priv, { __le16 key_flags; struct iwl_addsta_cmd sta_cmd; + size_t to_copy; int i; spin_lock_bh(&priv->sta_lock); @@ -1100,7 +1101,9 @@ static int iwlagn_send_sta_key(struct iwl_priv *priv, sta_cmd.key.tkip_rx_tsc_byte2 = tkip_iv32; for (i = 0; i < 5; i++) sta_cmd.key.tkip_rx_ttak[i] = cpu_to_le16(tkip_p1k[i]); - memcpy(sta_cmd.key.key, keyconf->key, keyconf->keylen); + /* keyconf may contain MIC rx/tx keys which iwl does not use */ + to_copy = min_t(size_t, sizeof(sta_cmd.key.key), keyconf->keylen); + memcpy(sta_cmd.key.key, keyconf->key, to_copy); break; case WLAN_CIPHER_SUITE_WEP104: key_flags |= STA_KEY_FLG_KEY_SIZE_MSK;
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> --- drivers/net/wireless/intel/iwlwifi/dvm/sta.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)