From: Zekun Shen bruceshenzk@gmail.com
[ Upstream commit 6ce708f54cc8d73beca213cec66ede5ce100a781 ]
Large pkt_len can lead to out-out-bound memcpy. Current ath9k_hif_usb_rx_stream allows combining the content of two urb inputs to one pkt. The first input can indicate the size of the pkt. Any remaining size is saved in hif_dev->rx_remain_len. While processing the next input, memcpy is used with rx_remain_len.
4-byte pkt_len can go up to 0xffff, while a single input is 0x4000 maximum in size (MAX_RX_BUF_SIZE). Thus, the patch adds a check for pkt_len which must not exceed 2 * MAX_RX_BUG_SIZE.
BUG: KASAN: slab-out-of-bounds in ath9k_hif_usb_rx_cb+0x490/0xed7 [ath9k_htc] Read of size 46393 at addr ffff888018798000 by task kworker/0:1/23
CPU: 0 PID: 23 Comm: kworker/0:1 Not tainted 5.6.0 #63 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.10.2-0-g5f4c7b1-prebuilt.qemu-project.org 04/01/2014 Workqueue: events request_firmware_work_func Call Trace: <IRQ> dump_stack+0x76/0xa0 print_address_description.constprop.0+0x16/0x200 ? ath9k_hif_usb_rx_cb+0x490/0xed7 [ath9k_htc] ? ath9k_hif_usb_rx_cb+0x490/0xed7 [ath9k_htc] __kasan_report.cold+0x37/0x7c ? ath9k_hif_usb_rx_cb+0x490/0xed7 [ath9k_htc] kasan_report+0xe/0x20 check_memory_region+0x15a/0x1d0 memcpy+0x20/0x50 ath9k_hif_usb_rx_cb+0x490/0xed7 [ath9k_htc] ? hif_usb_mgmt_cb+0x2d9/0x2d9 [ath9k_htc] ? _raw_spin_lock_irqsave+0x7b/0xd0 ? _raw_spin_trylock_bh+0x120/0x120 ? __usb_unanchor_urb+0x12f/0x210 __usb_hcd_giveback_urb+0x1e4/0x380 usb_giveback_urb_bh+0x241/0x4f0 ? __hrtimer_run_queues+0x316/0x740 ? __usb_hcd_giveback_urb+0x380/0x380 tasklet_action_common.isra.0+0x135/0x330 __do_softirq+0x18c/0x634 irq_exit+0x114/0x140 smp_apic_timer_interrupt+0xde/0x380 apic_timer_interrupt+0xf/0x20
I found the bug using a custome USBFuzz port. It's a research work to fuzz USB stack/drivers. I modified it to fuzz ath9k driver only, providing hand-crafted usb descriptors to QEMU.
After fixing the value of pkt_tag to ATH_USB_RX_STREAM_MODE_TAG in QEMU emulation, I found the KASAN report. The bug is triggerable whenever pkt_len is above two MAX_RX_BUG_SIZE. I used the same input that crashes to test the driver works when applying the patch.
Signed-off-by: Zekun Shen bruceshenzk@gmail.com Signed-off-by: Kalle Valo quic_kvalo@quicinc.com Link: https://lore.kernel.org/r/YXsidrRuK6zBJicZ@10-18-43-117.dynapool.wireless.ny... Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/wireless/ath/ath9k/hif_usb.c | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c index 2ed98aaed6fb5..c8c7afe0e343e 100644 --- a/drivers/net/wireless/ath/ath9k/hif_usb.c +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c @@ -590,6 +590,13 @@ static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev, return; }
+ if (pkt_len > 2 * MAX_RX_BUF_SIZE) { + dev_err(&hif_dev->udev->dev, + "ath9k_htc: invalid pkt_len (%x)\n", pkt_len); + RX_STAT_INC(skb_dropped); + return; + } + pad_len = 4 - (pkt_len & 0x3); if (pad_len == 4) pad_len = 0;