CVE-2026-74411: wifi: rtw89: Correct data type for scan index to avoid infinite loop

From: Greg Kroah-Hartman <[email protected]>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

wifi: rtw89: Correct data type for scan index to avoid infinite loop

A kernel soft lockup was observed during Wi-Fi scanning on the 6GHz band.
The CPU becomes stuck in rtw89_hw_scan_add_chan_ax for over 20 seconds,
leading to a system panic.

RIP points to 0f b6 c3 (movzbl %bl, %eax), which zero-extends
the low 8 bits of RBX into RAX.
RBX (the counter i) has reached a huge value: 0x137466a1.

  watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [kworker/u16:4:6124]
  Workqueue: events_unbound cfg80211_wiphy_work [cfg80211]
  RIP: 0010:rtw89_hw_scan_add_chan_ax+0xb3/0x6e0 [rtw89_core]
  Code: a0 48 89 45 a8 44 89 6d 9c 44 89 75 98 eb 29 66 66 2e 0f 1f
  84 00 00 00 00 00 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 83 c3 01
  <0f> b6 c3 41 3b 44 24 74 0f 83 0b 02 00 00 0f b6 c3 48 8d 14 80 49
  RSP: 0018:ffffcb48cbaa39f8 EFLAGS: 00000202
  RAX: 0000000000000005 RBX: 00000000137466a1 RCX: 0000000000000000
  RDX: ffff89ffc9d851a8 RSI: 0000000000004f0d RDI: 0000000096af0130
  RBP: ffffcb48cbaa3a60 R08: 0000000000000000 R09: ffff8a00b7502080
  R10: ffff8a00b75ff600 R11: 0000000000000000 R12: ffff89ffc7553870
  R13: ffff8a00b7ac8f19 R14: ffff8a00b75020d8 R15: ffff89ffc3d54d80
  FS:  0000000000000000(0000) GS:ffff8a014f962000(0000)
  knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007558d7f9f4c4 CR3: 0000000178040001 CR4: 00000000001706f0
  Call Trace:
   <TASK>
   rtw89_hw_scan_prep_chan_list_ax+0x8a/0x400 [rtw89_core]
   rtw89_hw_scan_start+0x546/0x8a0 [rtw89_core]
   ? rtw89_fw_h2c_default_cmac_tbl+0x13c/0x1f0 [rtw89_core]
   rtw89_ops_hw_scan+0xae/0x120 [rtw89_core]
   drv_hw_scan+0xbb/0x180 [mac80211]
   __ieee80211_start_scan+0x2fc/0x750 [mac80211]
   ieee80211_request_scan+0xe/0x20 [mac80211]
   ieee80211_scan+0x123/0x190 [mac80211]
   rdev_scan+0x40/0x110 [cfg80211]
   cfg80211_scan_6ghz+0x5a1/0xa30 [cfg80211]

By objdump with source:

	for (i = 0; i < req->n_6ghz_params; i++) {
   5fbc0:	83 c3 01             	add    $0x1,%ebx --> i++
   5fbc3:	0f b6 c3             	movzbl %bl,%eax  --> get counter
   fbc6:	41 3b 44 24 74       	cmp    0x74(%r12),%eax

   * RBX: 00000000137466a1 -> %bl = a1 -> EAX = 000000a1 (161)

The Linux kernel CVE team has assigned CVE-2026-74411 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.4 with commit c6aa9a9c47252ac7b07ed6d10459027e2f2a2de0 and fixed in 6.6.145 with commit 966fbed4b4463fbcb49c5becf3f86eae776861bd
	Issue introduced in 6.4 with commit c6aa9a9c47252ac7b07ed6d10459027e2f2a2de0 and fixed in 6.12.97 with commit 05d46e30303275f21f13c951166d39c85df976d4
	Issue introduced in 6.4 with commit c6aa9a9c47252ac7b07ed6d10459027e2f2a2de0 and fixed in 6.18.40 with commit 7a1ab5fdcae896e20ca6d68fa0fbd2816cb7471f
	Issue introduced in 6.4 with commit c6aa9a9c47252ac7b07ed6d10459027e2f2a2de0 and fixed in 7.1.5 with commit 140fa699cfd0e18ab2f1497acd951fb3548610f5
	Issue introduced in 6.4 with commit c6aa9a9c47252ac7b07ed6d10459027e2f2a2de0 and fixed in 7.2-rc1 with commit 08fdcb529df6df3562dd2b0035f88dd5be8b3c68

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-74411
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/net/wireless/realtek/rtw89/fw.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/966fbed4b4463fbcb49c5becf3f86eae776861bd
	https://git.kernel.org/stable/c/05d46e30303275f21f13c951166d39c85df976d4
	https://git.kernel.org/stable/c/7a1ab5fdcae896e20ca6d68fa0fbd2816cb7471f
	https://git.kernel.org/stable/c/140fa699cfd0e18ab2f1497acd951fb3548610f5
	https://git.kernel.org/stable/c/08fdcb529df6df3562dd2b0035f88dd5be8b3c68