[PATCH] rtlwifi: Fix null-pointer dereferences in error handling code of rtl_pci_probe()

* [PATCH] rtlwifi: Fix null-pointer dereferences in error handling code of rtl_pci_probe()
@ 2019-05-14 12:34 Jia-Ju Bai
  2019-05-28 11:55 ` Kalle Valo
  0 siblings, 1 reply; 6+ messages in thread
From: Jia-Ju Bai @ 2019-05-14 12:34 UTC (permalink / raw)
  To: pkshih, kvalo, davem; +Cc: linux-wireless, netdev, linux-kernel, Jia-Ju Bai

*BUG 1:
In rtl_pci_probe(), when rtlpriv->cfg->ops->init_sw_vars() fails,
rtl_deinit_core() in the error handling code is executed.
rtl_deinit_core() calls rtl_free_entries_from_scan_list(), which uses
rtlpriv->scan_list.list in list_for_each_entry_safe(), but it has been
initialized. Thus a null-pointer dereference occurs.
The reason is that rtlpriv->scan_list.list is initialized by
INIT_LIST_HEAD() in rtl_init_core(), which has not been called.

To fix this bug, rtl_deinit_core() should not be called when
rtlpriv->cfg->ops->init_sw_vars() fails.

*BUG 2:
In rtl_pci_probe(), rtl_init_core() can fail when rtl_regd_init() in
this function fails, and rtlpriv->scan_list.list has not been
initialized by INIT_LIST_HEAD(). Then, rtl_deinit_core() in the error
handling code of rtl_pci_probe() is executed. Finally, a null-pointer
dereference occurs due to the same reason of the above bug.

To fix this bug, the initialization of lists in rtl_init_core() are
performed before the call to rtl_regd_init().

These bugs are found by a runtime fuzzing tool named FIZZER written by
us.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
 drivers/net/wireless/realtek/rtlwifi/base.c | 15 ++++++++-------
 drivers/net/wireless/realtek/rtlwifi/pci.c  |  4 ++--
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/net/wireless/realtek/rtlwifi/base.c b/drivers/net/wireless/realtek/rtlwifi/base.c
index 217d2a7a43c7..b3f341ec3710 100644
--- a/drivers/net/wireless/realtek/rtlwifi/base.c
+++ b/drivers/net/wireless/realtek/rtlwifi/base.c
@@ -526,8 +526,14 @@ int rtl_init_core(struct ieee80211_hw *hw)
 	/* <2> rate control register */
 	hw->rate_control_algorithm = "rtl_rc";
 
+	/* <3> init list */
+	INIT_LIST_HEAD(&rtlpriv->entry_list);
+	INIT_LIST_HEAD(&rtlpriv->scan_list.list);
+	skb_queue_head_init(&rtlpriv->tx_report.queue);
+	skb_queue_head_init(&rtlpriv->c2hcmd_queue);
+
 	/*
-	 * <3> init CRDA must come after init
+	 * <4> init CRDA must come after init
 	 * mac80211 hw  in _rtl_init_mac80211.
 	 */
 	if (rtl_regd_init(hw, rtl_reg_notifier)) {
@@ -535,7 +541,7 @@ int rtl_init_core(struct ieee80211_hw *hw)
 		return 1;
 	}
 
-	/* <4> locks */
+	/* <5> locks */
 	mutex_init(&rtlpriv->locks.conf_mutex);
 	mutex_init(&rtlpriv->locks.ips_mutex);
 	mutex_init(&rtlpriv->locks.lps_mutex);
@@ -550,11 +556,6 @@ int rtl_init_core(struct ieee80211_hw *hw)
 	spin_lock_init(&rtlpriv->locks.cck_and_rw_pagea_lock);
 	spin_lock_init(&rtlpriv->locks.fw_ps_lock);
 	spin_lock_init(&rtlpriv->locks.iqk_lock);
-	/* <5> init list */
-	INIT_LIST_HEAD(&rtlpriv->entry_list);
-	INIT_LIST_HEAD(&rtlpriv->scan_list.list);
-	skb_queue_head_init(&rtlpriv->tx_report.queue);
-	skb_queue_head_init(&rtlpriv->c2hcmd_queue);
 
 	rtlmac->link_state = MAC80211_NOLINK;
 
diff --git a/drivers/net/wireless/realtek/rtlwifi/pci.c b/drivers/net/wireless/realtek/rtlwifi/pci.c
index 48ca52102cef..864cb76230c4 100644
--- a/drivers/net/wireless/realtek/rtlwifi/pci.c
+++ b/drivers/net/wireless/realtek/rtlwifi/pci.c
@@ -2267,7 +2267,7 @@ int rtl_pci_probe(struct pci_dev *pdev,
 	if (rtlpriv->cfg->ops->init_sw_vars(hw)) {
 		pr_err("Can't init_sw_vars\n");
 		err = -ENODEV;
-		goto fail3;
+		goto fail2;
 	}
 	rtlpriv->cfg->ops->init_sw_leds(hw);
-- 
2.17.0


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