[PATCH rtw-next 1/8] wifi: rtw89: pci: validate sequence number of TX release report

[Ping-Ke Shih <pkshih@realtek.com>]

Hardware rarely reports abnormal sequence number in TX release report,
which will access out-of-bounds of wd_ring->pages array, causing NULL
pointer dereference.

  BUG: kernel NULL pointer dereference, address: 0000000000000000
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 1 PID: 1085 Comm: irq/129-rtw89_p Tainted: G S   U
             6.1.145-17510-g2f3369c91536 #1 (HASH:69e8 1)
  Call Trace:
   <IRQ>
   rtw89_pci_release_tx+0x18f/0x300 [rtw89_pci (HASH:4c83 2)]
   rtw89_pci_napi_poll+0xc2/0x190 [rtw89_pci (HASH:4c83 2)]
   net_rx_action+0xfc/0x460 net/core/dev.c:6578 net/core/dev.c:6645 net/core/dev.c:6759
   handle_softirqs+0xbe/0x290 kernel/softirq.c:601
   ? rtw89_pci_interrupt_threadfn+0xc5/0x350 [rtw89_pci (HASH:4c83 2)]
   __local_bh_enable_ip+0xeb/0x120 kernel/softirq.c:499 kernel/softirq.c:423
   </IRQ>
   <TASK>
   rtw89_pci_interrupt_threadfn+0xf8/0x350 [rtw89_pci (HASH:4c83 2)]
   ? irq_thread+0xa7/0x340 kernel/irq/manage.c:0
   irq_thread+0x177/0x340 kernel/irq/manage.c:1205 kernel/irq/manage.c:1314
   ? thaw_kernel_threads+0xb0/0xb0 kernel/irq/manage.c:1202
   ? irq_forced_thread_fn+0x80/0x80 kernel/irq/manage.c:1220
   kthread+0xea/0x110 kernel/kthread.c:376
   ? synchronize_irq+0x1a0/0x1a0 kernel/irq/manage.c:1287
   ? kthread_associate_blkcg+0x80/0x80 kernel/kthread.c:331
   ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
   </TASK>

To prevent crash, validate rpp_info.seq before using.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
---
 drivers/net/wireless/realtek/rtw89/pci.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/realtek/rtw89/pci.c b/drivers/net/wireless/realtek/rtw89/pci.c
index a66fcdb0293b..093960d7279f 100644
--- a/drivers/net/wireless/realtek/rtw89/pci.c
+++ b/drivers/net/wireless/realtek/rtw89/pci.c
@@ -604,11 +604,16 @@ static void rtw89_pci_release_rpp(struct rtw89_dev *rtwdev, void *rpp)
 
 	info->parse_rpp(rtwdev, rpp, &rpp_info);
 
-	if (rpp_info.txch == RTW89_TXCH_CH12) {
+	if (unlikely(rpp_info.txch == RTW89_TXCH_CH12)) {
 		rtw89_warn(rtwdev, "should no fwcmd release report\n");
 		return;
 	}
 
+	if (unlikely(rpp_info.seq >= RTW89_PCI_TXWD_NUM_MAX)) {
+		rtw89_warn(rtwdev, "invalid seq %d\n", rpp_info.seq);
+		return;
+	}
+
 	tx_ring = &rtwpci->tx.rings[rpp_info.txch];
 	wd_ring = &tx_ring->wd_ring;
 	txwd = &wd_ring->pages[rpp_info.seq];
-- 
2.25.1