From: Zekun Shen <bruceshenzk@xxxxxxxxx> [ Upstream commit b07e3c6ebc0c20c772c0f54042e430acec2945c3 ] When freeing rx_cb->rx_skb, the pointer is not set to NULL, a later rsi_rx_done_handler call will try to read the freed address. This bug will very likley lead to double free, although detected early as use-after-free bug. The bug is triggerable with a compromised/malfunctional usb device. After applying the patch, the same input no longer triggers the use-after-free. Attached is the kasan report from fuzzing. BUG: KASAN: use-after-free in rsi_rx_done_handler+0x354/0x430 [rsi_usb] Read of size 4 at addr ffff8880188e5930 by task modprobe/231 Call Trace: <IRQ> dump_stack+0x76/0xa0 print_address_description.constprop.0+0x16/0x200 ? rsi_rx_done_handler+0x354/0x430 [rsi_usb] ? rsi_rx_done_handler+0x354/0x430 [rsi_usb] __kasan_report.cold+0x37/0x7c ? dma_direct_unmap_page+0x90/0x110 ? rsi_rx_done_handler+0x354/0x430 [rsi_usb] kasan_report+0xe/0x20 rsi_rx_done_handler+0x354/0x430 [rsi_usb] __usb_hcd_giveback_urb+0x1e4/0x380 usb_giveback_urb_bh+0x241/0x4f0 ? __usb_hcd_giveback_urb+0x380/0x380 ? apic_timer_interrupt+0xa/0x20 tasklet_action_common.isra.0+0x135/0x330 __do_softirq+0x18c/0x634 ? handle_irq_event+0xcd/0x157 ? handle_edge_irq+0x1eb/0x7b0 irq_exit+0x114/0x140 do_IRQ+0x91/0x1e0 common_interrupt+0xf/0xf </IRQ> Reported-by: Brendan Dolan-Gavitt <brendandg@xxxxxxx> Signed-off-by: Zekun Shen <bruceshenzk@xxxxxxxxx> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/YXxQL/vIiYcZUu/j@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/net/wireless/rsi/rsi_91x_usb.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/rsi/rsi_91x_usb.c b/drivers/net/wireless/rsi/rsi_91x_usb.c index 68ce3d2bc5357..730d7bf86c40c 100644 --- a/drivers/net/wireless/rsi/rsi_91x_usb.c +++ b/drivers/net/wireless/rsi/rsi_91x_usb.c @@ -261,8 +261,12 @@ static void rsi_rx_done_handler(struct urb *urb) struct rsi_91x_usbdev *dev = (struct rsi_91x_usbdev *)rx_cb->data; int status = -EINVAL; + if (!rx_cb->rx_skb) + return; + if (urb->status) { dev_kfree_skb(rx_cb->rx_skb); + rx_cb->rx_skb = NULL; return; } @@ -286,8 +290,10 @@ out: if (rsi_rx_urb_submit(dev->priv, rx_cb->ep_num, GFP_ATOMIC)) rsi_dbg(ERR_ZONE, "%s: Failed in urb submission", __func__); - if (status) + if (status) { dev_kfree_skb(rx_cb->rx_skb); + rx_cb->rx_skb = NULL; + } } static void rsi_rx_urb_kill(struct rsi_hw *adapter, u8 ep_num) -- 2.34.1
