[PATCH 4.18 44/44] ath10k: fix scan crash due to incorrect length calculation

From: Greg Kroah-Hartman
Date: Thu Oct 11 2018 - 11:49:14 EST


4.18-stable review patch. If anyone has any objections, please let me know.

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

From: Zhi Chen <zhichen@xxxxxxxxxxxxxx>

commit c8291988806407e02a01b4b15b4504eafbcc04e0 upstream.

Length of WMI scan message was not calculated correctly. The allocated
buffer was smaller than what we expected. So WMI message corrupted
skb_info, which is at the end of skb->data. This fix takes TLV header
into account even if the element is zero-length.

Crash log:
[49.629986] Unhandled kernel unaligned access[#1]:
[49.634932] CPU: 0 PID: 1176 Comm: logd Not tainted 4.4.60 #180
[49.641040] task: 83051460 ti: 8329c000 task.ti: 8329c000
[49.646608] $ 0 : 00000000 00000001 80984a80 00000000
[49.652038] $ 4 : 45259e89 8046d484 8046df30 8024ba70
[49.657468] $ 8 : 00000000 804cc4c0 00000001 20306320
[49.662898] $12 : 33322037 000110f2 00000000 31203930
[49.668327] $16 : 82792b40 80984a80 00000001 804207fc
[49.673757] $20 : 00000000 0000012c 00000040 80470000
[49.679186] $24 : 00000000 8024af7c
[49.684617] $28 : 8329c000 8329db88 00000001 802c58d0
[49.690046] Hi : 00000000
[49.693022] Lo : 453c0000
[49.696013] epc : 800efae4 put_page+0x0/0x58
[49.700615] ra : 802c58d0 skb_release_data+0x148/0x1d4
[49.706184] Status: 1000fc03 KERNEL EXL IE
[49.710531] Cause : 00800010 (ExcCode 04)
[49.714669] BadVA : 45259e89
[49.717644] PrId : 00019374 (MIPS 24Kc)

Signed-off-by: Zhi Chen <zhichen@xxxxxxxxxxxxxx>
Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
Cc: Brian Norris <briannorris@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/net/wireless/ath/ath10k/wmi-tlv.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

--- a/drivers/net/wireless/ath/ath10k/wmi-tlv.c
+++ b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
@@ -1619,10 +1619,10 @@ ath10k_wmi_tlv_op_gen_start_scan(struct
bssid_len = arg->n_bssids * sizeof(struct wmi_mac_addr);
ie_len = roundup(arg->ie_len, 4);
len = (sizeof(*tlv) + sizeof(*cmd)) +
- (arg->n_channels ? sizeof(*tlv) + chan_len : 0) +
- (arg->n_ssids ? sizeof(*tlv) + ssid_len : 0) +
- (arg->n_bssids ? sizeof(*tlv) + bssid_len : 0) +
- (arg->ie_len ? sizeof(*tlv) + ie_len : 0);
+ sizeof(*tlv) + chan_len +
+ sizeof(*tlv) + ssid_len +
+ sizeof(*tlv) + bssid_len +
+ sizeof(*tlv) + ie_len;

skb = ath10k_wmi_alloc_skb(ar, len);
if (!skb)