Subject: CVE-2024-43911: wifi: mac80211: fix NULL dereference at band check in starting tx ba session

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

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

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

wifi: mac80211: fix NULL dereference at band check in starting tx ba session

In MLD connection, link_data/link_conf are dynamically allocated. They
don't point to vif->bss_conf. So, there will be no chanreq assigned to
vif->bss_conf and then the chan will be NULL. Tweak the code to check
ht_supported/vht_supported/has_he/has_eht on sta deflink.

Crash log (with rtw89 version under MLO development):
[ 9890.526087] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 9890.526102] #PF: supervisor read access in kernel mode
[ 9890.526105] #PF: error_code(0x0000) - not-present page
[ 9890.526109] PGD 0 P4D 0
[ 9890.526114] Oops: 0000 [#1] PREEMPT SMP PTI
[ 9890.526119] CPU: 2 PID: 6367 Comm: kworker/u16:2 Kdump: loaded Tainted: G           OE      6.9.0 #1
[ 9890.526123] Hardware name: LENOVO 2356AD1/2356AD1, BIOS G7ETB3WW (2.73 ) 11/28/2018
[ 9890.526126] Workqueue: phy2 rtw89_core_ba_work [rtw89_core]
[ 9890.526203] RIP: 0010:ieee80211_start_tx_ba_session (net/mac80211/agg-tx.c:618 (discriminator 1)) mac80211
[ 9890.526279] Code: f7 e8 d5 93 3e ea 48 83 c4 28 89 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 49 8b 84 24 e0 f1 ff ff 48 8b 80 90 1b 00 00 <83> 38 03 0f 84 37 fe ff ff bb ea ff ff ff eb cc 49 8b 84 24 10 f3
All code
========
   0:	f7 e8                	imul   %eax
   2:	d5                   	(bad)
   3:	93                   	xchg   %eax,%ebx
   4:	3e ea                	ds (bad)
   6:	48 83 c4 28          	add    $0x28,%rsp
   a:	89 d8                	mov    %ebx,%eax
   c:	5b                   	pop    %rbx
   d:	41 5c                	pop    %r12
   f:	41 5d                	pop    %r13
  11:	41 5e                	pop    %r14
  13:	41 5f                	pop    %r15
  15:	5d                   	pop    %rbp
  16:	c3                   	retq
  17:	cc                   	int3
  18:	cc                   	int3
  19:	cc                   	int3
  1a:	cc                   	int3
  1b:	49 8b 84 24 e0 f1 ff 	mov    -0xe20(%r12),%rax
  22:	ff
  23:	48 8b 80 90 1b 00 00 	mov    0x1b90(%rax),%rax
  2a:*	83 38 03             	cmpl   $0x3,(%rax)		<-- trapping instruction
  2d:	0f 84 37 fe ff ff    	je     0xfffffffffffffe6a
  33:	bb ea ff ff ff       	mov    $0xffffffea,%ebx
  38:	eb cc                	jmp    0x6
  3a:	49                   	rex.WB
  3b:	8b                   	.byte 0x8b
  3c:	84 24 10             	test   %ah,(%rax,%rdx,1)
  3f:	f3                   	repz

Code starting with the faulting instruction
===========================================
   0:	83 38 03             	cmpl   $0x3,(%rax)
   3:	0f 84 37 fe ff ff    	je     0xfffffffffffffe40
   9:	bb ea ff ff ff       	mov    $0xffffffea,%ebx
   e:	eb cc                	jmp    0xffffffffffffffdc
  10:	49                   	rex.WB
  11:	8b                   	.byte 0x8b
  12:	84 24 10             	test   %ah,(%rax,%rdx,1)
  15:	f3                   	repz
[ 9890.526285] RSP: 0018:ffffb8db09013d68 EFLAGS: 00010246
[ 9890.526291] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff9308e0d656c8
[ 9890.526295] RDX: 0000000000000000 RSI: ffffffffab99460b RDI: ffffffffab9a7685
[ 9890.526300] RBP: ffffb8db09013db8 R08: 0000000000000000 R09: 0000000000000873
[ 9890.526304] R10: ffff9308e0d64800 R11: 0000000000000002 R12: ffff9308e5ff6e70
[ 9890.526308] R13: ffff930952500e20 R14: ffff9309192a8c00 R15: 0000000000000000
[ 9890.526313] FS:  0000000000000000(0000) GS:ffff930b4e700000(0000) knlGS:0000000000000000
[ 9890.526316] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9890.526318] CR2: 0000000000000000 CR3: 0000000391c58005 CR4: 00000000001706f0
[ 9890.526321] Call Trace:
[ 9890.526324]  <TASK>
[ 9890.526327] ? show_regs (arch/x86/kernel/dumpstack.c:479)
[ 9890.526335] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434)
[ 9890.526340] ? page_fault_oops (arch/x86/mm/fault.c:713)
[ 9890.526347] ? search_module_extables (kernel/module/main.c:3256 (discriminator 3))
[ 9890.526353] ? ieee80211_start_tx_ba_session (net/mac80211/agg-tx.c:618 (discriminator 1)) mac80211

The Linux kernel CVE team has assigned CVE-2024-43911 to this issue.

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

	Fixed in 6.10.5 with commit a5594c1e03b0
	Fixed in 6.11 with commit 021d53a3d87e

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-2024-43911
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:
	net/mac80211/agg-tx.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/a5594c1e03b0df3908b1e1202a1ba34422eed0f6
	https://git.kernel.org/stable/c/021d53a3d87eeb9dbba524ac515651242a2a7e3b