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authorMohammed Shafi Shajakhan <mohammed@qca.qualcomm.com>2012-11-16 13:52:40 +0100
committerKalle Valo <kvalo@qca.qualcomm.com>2012-11-27 20:44:27 +0100
commitde2070fc4aa7c0205348010f500f5abce012e67b (patch)
treed0a7ab9d6f0acd309678890d7762d565210ebd38 /drivers
parentath6kl: remove unnecessary check for NULL skb (diff)
downloadlinux-de2070fc4aa7c0205348010f500f5abce012e67b.tar.xz
linux-de2070fc4aa7c0205348010f500f5abce012e67b.zip
ath6kl: Fix kernel panic on continuous driver load/unload
On continuous loading and unloading of AR6004 ath6kl USB driver it triggers a panic due to NULL pointer dereference of 'target' pointer. while true; do sudo modprobe -v ath6kl_core; sudo modprobe -v ath6kl_usb; sudo modprobe -r usb; sudo modprobe -r ath6kl_core; done ar->htc_target can be NULL due to a race condition that can occur during driver initialization(we do 'ath6kl_hif_power_on' before initializing 'ar->htc_target' via 'ath6kl_htc_create'). 'ath6kl_hif_power_on' assigns 'ath6kl_recv_complete' as usb_complete_t/callback function for 'usb_fill_bulk_urb'. Thus the possibility of ar->htc_target being NULL via ath6kl_recv_complete -> ath6kl_usb_io_comp_work before even 'ath6kl_htc_create' is finished to initialize ar->htc_create. Worth noting is the obvious solution of doing 'ath6kl_hif_power_on' later(i.e after we are done with 'ath6kl_htc_create', causes a h/w bring up failure in AR6003 SDIO, as 'ath6kl_hif_power_on' is a pre-requisite to get the target version 'ath6kl_bmi_get_target_info'. So simply check for NULL pointer for 'ar->htc_target' and bail out. [23614.518282] BUG: unable to handle kernel NULL pointer dereference at 00000904 [23614.518463] IP: [<c012e7a6>] __ticket_spin_trylock+0x6/0x30 [23614.518570] *pde = 00000000 [23614.518664] Oops: 0000 [#1] SMP [23614.518795] Modules linked in: ath6kl_usb(O+) ath6kl_core(O) [23614.520012] EIP: 0060:[<c012e7a6>] EFLAGS: 00010286 CPU: 0 [23614.520012] EIP is at __ticket_spin_trylock+0x6/0x30 Call Trace: [<c03f2a44>] do_raw_spin_trylock+0x14/0x40 [<c06daa12>] _raw_spin_lock_bh+0x52/0x80 [<f85464b4>] ? ath6kl_htc_pipe_rx_complete+0x3b4/0x4c0 [ath6kl_core] [<f85464b4>] ath6kl_htc_pipe_rx_complete+0x3b4/0x4c0 [ath6kl_core] [<c05bc272>] ? skb_dequeue+0x22/0x70 [<c05bc272>] ? skb_dequeue+0x22/0x70 [<f855bb32>] ath6kl_core_rx_complete+0x12/0x20 [ath6kl_core] [<f848771a>] ath6kl_usb_io_comp_work+0xaa/0xb0 [ath6kl_usb] [<c015b863>] process_one_work+0x1a3/0x5e0 [<c015b7e7>] ? process_one_work+0x127/0x5e0 [<f8487670>] ? ath6kl_usb_reset_resume+0x30/0x30 [ath6kl_usb] [<c015bfde>] worker_thread+0x11e/0x3f0 Kernel panic - not syncing: Fatal exception in interrupt Signed-off-by: Mohammed Shafi Shajakhan <mohammed@qca.qualcomm.com> Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/net/wireless/ath/ath6kl/htc_pipe.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/net/wireless/ath/ath6kl/htc_pipe.c b/drivers/net/wireless/ath/ath6kl/htc_pipe.c
index 73a38f9392f9..281390178e3d 100644
--- a/drivers/net/wireless/ath/ath6kl/htc_pipe.c
+++ b/drivers/net/wireless/ath/ath6kl/htc_pipe.c
@@ -967,6 +967,22 @@ static int ath6kl_htc_pipe_rx_complete(struct ath6kl *ar, struct sk_buff *skb,
u16 payload_len;
int status = 0;
+ /*
+ * ar->htc_target can be NULL due to a race condition that can occur
+ * during driver initialization(we do 'ath6kl_hif_power_on' before
+ * initializing 'ar->htc_target' via 'ath6kl_htc_create').
+ * 'ath6kl_hif_power_on' assigns 'ath6kl_recv_complete' as
+ * usb_complete_t/callback function for 'usb_fill_bulk_urb'.
+ * Thus the possibility of ar->htc_target being NULL
+ * via ath6kl_recv_complete -> ath6kl_usb_io_comp_work.
+ */
+ if (WARN_ON_ONCE(!target)) {
+ ath6kl_err("Target not yet initialized\n");
+ status = -EINVAL;
+ goto free_skb;
+ }
+
+
netdata = skb->data;
netlen = skb->len;