From 4cd4b50cc2429294c23a1998c33fdfd804db0f37 Mon Sep 17 00:00:00 2001 From: Emmanuel Grumbach Date: Thu, 5 Mar 2015 13:43:15 +0200 Subject: [PATCH] iwlwifi: mvm: BT Coex - fix a NULL pointer exception The commit below introduced an unsafe dereference of mvmvif->phy_ctxt. It can be NULL even if we hold the mutex. We can be handling a BT Coex notification while the vif has already been unassigned. This can happen since the BT Coex notification is hanled asynchronuously: we can have started to handle the BT Coex notification trying to acquire the mutex while the unassign flow already got it. The BT Coex notification handling will wait for the mutext. I'll get it later, but then mvmvif->phy_ctxt will be NULL. Panic log: BUG: unable to handle kernel NULL pointer dereference at (null) IP: [] iwl_mvm_bt_notif_iterator+0x9d/0x340 [iwlmvm] *pdpt = 0000000000000000 *pde = f000eef300000007 Oops: 0000 [#1] SMP Workqueue: events iwl_mvm_async_handlers_wk [iwlmvm] task: ed719b20 ti: ec03e000 task.ti: ec03e000 EIP: 0060:[] EFLAGS: 00010202 CPU: 2 EIP is at iwl_mvm_bt_notif_iterator+0x9d/0x340 [iwlmvm] EAX: 00000000 EBX: f6d3cb70 ECX: f6d3cb70 EDX: 00000000 ESI: ec03fe40 EDI: efeb8810 EBP: ec03fdf0 ESP: ec03fdac DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 CR0: 80050033 CR2: 00000000 CR3: 01a1a000 CR4: 001407f0 Stack: f743ca80 f744a404 ec03fdcc c10e3952 00003aba f743ca80 00000246 f743ca80 00000246 00000000 00000001 00000000 ebd45ff6 ebd458a4 f6d3c500 ebd45578 ebd44b01 ec03fe18 f99e1bc2 00000002 ebd44bc0 f9851770 00000000 f6d3c500 Call Trace: [] ? ring_buffer_unlock_commit+0xa2/0xd0 [] __iterate_interfaces+0x82/0x110 [mac80211] [] ? iwl_mvm_bt_coex_reduced_txp+0x140/0x140 [iwlmvm] [] ieee80211_iterate_active_interfaces_atomic+0x1a/0x20 [mac80211] [] iwl_mvm_bt_coex_notif_handle+0x77/0x280 [iwlmvm] [] iwl_mvm_rx_bt_coex_notif_old+0x211/0x220 [iwlmvm] [] iwl_mvm_rx_bt_coex_notif+0x19b/0x1b0 [iwlmvm] [] iwl_mvm_async_handlers_wk+0x7f/0xe0 [iwlmvm] CC: [3.19+] Fixes: 123f515635b1 ("iwlwifi: mvm: BT Coex - add support for TTC / RRC") Signed-off-by: Emmanuel Grumbach --- drivers/net/wireless/iwlwifi/mvm/coex.c | 3 ++- drivers/net/wireless/iwlwifi/mvm/coex_legacy.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/mvm/coex.c b/drivers/net/wireless/iwlwifi/mvm/coex.c index 1ec4d55155f7..7810c41cf9a7 100644 --- a/drivers/net/wireless/iwlwifi/mvm/coex.c +++ b/drivers/net/wireless/iwlwifi/mvm/coex.c @@ -793,7 +793,8 @@ static void iwl_mvm_bt_notif_iterator(void *_data, u8 *mac, if (!vif->bss_conf.assoc) smps_mode = IEEE80211_SMPS_AUTOMATIC; - if (IWL_COEX_IS_RRC_ON(mvm->last_bt_notif.ttc_rrc_status, + if (mvmvif->phy_ctxt && + IWL_COEX_IS_RRC_ON(mvm->last_bt_notif.ttc_rrc_status, mvmvif->phy_ctxt->id)) smps_mode = IEEE80211_SMPS_AUTOMATIC; diff --git a/drivers/net/wireless/iwlwifi/mvm/coex_legacy.c b/drivers/net/wireless/iwlwifi/mvm/coex_legacy.c index d530ef3da107..542ee74f290a 100644 --- a/drivers/net/wireless/iwlwifi/mvm/coex_legacy.c +++ b/drivers/net/wireless/iwlwifi/mvm/coex_legacy.c @@ -832,7 +832,8 @@ static void iwl_mvm_bt_notif_iterator(void *_data, u8 *mac, if (!vif->bss_conf.assoc) smps_mode = IEEE80211_SMPS_AUTOMATIC; - if (data->notif->rrc_enabled & BIT(mvmvif->phy_ctxt->id)) + if (mvmvif->phy_ctxt && + data->notif->rrc_enabled & BIT(mvmvif->phy_ctxt->id)) smps_mode = IEEE80211_SMPS_AUTOMATIC; IWL_DEBUG_COEX(data->mvm, -- 2.34.1