KASAN: slab-out-of-bounds Write in ath9k_htc_rx_msg

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    e17994d1 usb: core: kcov: collect coverage from usb comple..
git tree:       https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=1409ca5be00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5d64370c438bc60
dashboard link: https://syzkaller.appspot.com/bug?extid=694d40a36a6452d77f36
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=122d48f3e00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=122511e5e00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+694d40a36a6452d77f36@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: slab-out-of-bounds in htc_process_conn_rsp drivers/net/wireless/ath/ath9k/htc_hst.c:131 [inline]
BUG: KASAN: slab-out-of-bounds in ath9k_htc_rx_msg+0xa25/0xaf0 drivers/net/wireless/ath/ath9k/htc_hst.c:443
Write of size 2 at addr ffff8881ced8a7f0 by task swapper/0/0

CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0xef/0x16e lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x314 mm/kasan/report.c:374
 __kasan_report.cold+0x37/0x77 mm/kasan/report.c:506
 kasan_report+0xe/0x20 mm/kasan/common.c:641
 htc_process_conn_rsp drivers/net/wireless/ath/ath9k/htc_hst.c:131 [inline]
 ath9k_htc_rx_msg+0xa25/0xaf0 drivers/net/wireless/ath/ath9k/htc_hst.c:443
 ath9k_hif_usb_reg_in_cb+0x1ba/0x630 drivers/net/wireless/ath/ath9k/hif_usb.c:718
 __usb_hcd_giveback_urb+0x29a/0x550 drivers/usb/core/hcd.c:1650
 usb_hcd_giveback_urb+0x368/0x420 drivers/usb/core/hcd.c:1716
 dummy_timer+0x1258/0x32ae drivers/usb/gadget/udc/dummy_hcd.c:1966


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