linux-kernel - [024/102] ath6kl: fix crash when interface is closed but scan is ongoing

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Date:	Wed, 03 Aug 2011 15:00:44 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Kalle Valo <kvalo@....qualcomm.com>
Subject: [024/102] ath6kl: fix crash when interface is closed but scan is ongoing

3.0-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Kalle Valo <kvalo@....qualcomm.com>

commit 98ab5c7755b5cc9e1a8f2a57ccb22eac5e13ec50 upstream.

When ath6kl module was resumed while a scan was ongoing, for example during
suspend, the driver would crash in ar6k_cfg80211_scanComplete_event():

[26581.586440] Call Trace:
[26581.586440]  [<f99ffeda>] ? ar6k_cfg80211_scanComplete_event+0xaa/0xaa [ath6kl]
[26581.586440]  [<f9a0a020>] wmi_iterate_nodes+0xb/0xd [ath6kl]
[26581.586440]  [<f99ffe78>] ar6k_cfg80211_scanComplete_event+0x48/0xaa [ath6kl]
[26581.586440]  [<f9a038ae>] ar6000_close+0x77/0x7e [ath6kl]
[26581.586440]  [<c139c25d>] __dev_close_many+0x87/0xab
[26581.586440]  [<c139c30a>] dev_close_many+0x54/0xab
[26581.586440]  [<c139c437>] rollback_registered_many+0xa5/0x19e
[26581.586440]  [<c139c595>] rollback_registered+0x23/0x2f
[26581.586440]  [<c139c5ed>] unregister_netdevice_queue+0x4c/0x69
[26581.586440]  [<c139c6b2>] unregister_netdev+0x18/0x1f
[26581.586440]  [<f9a00d4c>] ar6000_destroy+0xf8/0x115 [ath6kl]
[26581.586440]  [<f9a0c765>] ar6k_cleanup_module+0x20/0x29 [ath6kl]
[26581.586440]  [<c1062843>] sys_delete_module+0x181/0x1d9
[26581.586440]  [<c105876b>] ? lock_release_holdtime+0x2b/0xcd
[26581.586440]  [<c10b55dc>] ? sys_munmap+0x3b/0x42
[26581.586440]  [<c14a99dc>] ? restore_all+0xf/0xf
[26581.586440]  [<c14aeb6c>] sysenter_do_call+0x12/0x32
[26581.586440] Code: 89 53 6c 75 07 89 d8 e8 c0 ff ff ff 89 f0 e8 2c f2 a9 c7 5b 5e 5d c3 55 89 e5 57 56 53 89 c3 83 ec 08 89 55 f0 8d 78 04 89 4d ec <8b> b0 b8 00 00 00 46 89 b0 b8 00 00 00 89 f8 e8 ae ed a9 c7 8b

Fix the function not to iterate nodes when the scan is aborted. The nodes
are already freed when the module is being unloaded. Patch "ath6kl: Fix a
kernel panic furing suspend/resume" tried to fix this already but it wasn't
enough as a pointer was still used even after the null check. This patch
removes the null check entirely as the wmi structure is not accessed anymore
during module unload.

Also fix a bug where the status was checked as a bitfield with '&' operator.
But it's not a bitfield, just a regular (enum like) value.

Signed-off-by: Kalle Valo <kvalo@....qualcomm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/staging/ath6kl/os/linux/cfg80211.c |   31 ++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

--- a/drivers/staging/ath6kl/os/linux/cfg80211.c
+++ b/drivers/staging/ath6kl/os/linux/cfg80211.c
@@ -867,26 +867,31 @@ ar6k_cfg80211_scanComplete_event(struct
 
     AR_DEBUG_PRINTF(ATH_DEBUG_INFO, ("%s: status %d\n", __func__, status));
 
-    if(ar->scan_request)
-    {
-        /* Translate data to cfg80211 mgmt format */
-	if (ar->arWmi)
-		wmi_iterate_nodes(ar->arWmi, ar6k_cfg80211_scan_node, ar->wdev->wiphy);
+    if (!ar->scan_request)
+	    return;
 
-        cfg80211_scan_done(ar->scan_request,
-            ((status & A_ECANCELED) || (status & A_EBUSY)) ? true : false);
+    if ((status == A_ECANCELED) || (status == A_EBUSY)) {
+	    cfg80211_scan_done(ar->scan_request, true);
+	    goto out;
+    }
+
+    /* Translate data to cfg80211 mgmt format */
+    wmi_iterate_nodes(ar->arWmi, ar6k_cfg80211_scan_node, ar->wdev->wiphy);
 
-        if(ar->scan_request->n_ssids &&
-           ar->scan_request->ssids[0].ssid_len) {
+    cfg80211_scan_done(ar->scan_request, false);
+
+    if(ar->scan_request->n_ssids &&
+       ar->scan_request->ssids[0].ssid_len) {
             u8 i;
 
             for (i = 0; i < ar->scan_request->n_ssids; i++) {
-                wmi_probedSsid_cmd(ar->arWmi, i+1, DISABLE_SSID_FLAG,
-                                   0, NULL);
+		    wmi_probedSsid_cmd(ar->arWmi, i+1, DISABLE_SSID_FLAG,
+				       0, NULL);
             }
-        }
-        ar->scan_request = NULL;
     }
+
+out:
+    ar->scan_request = NULL;
 }
 
 static int


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