Subject: CVE-2023-52889: apparmor: Fix null pointer deref when receiving skb during sock creation

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

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

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

apparmor: Fix null pointer deref when receiving skb during sock creation

The panic below is observed when receiving ICMP packets with secmark set
while an ICMP raw socket is being created. SK_CTX(sk)->label is updated
in apparmor_socket_post_create(), but the packet is delivered to the
socket before that, causing the null pointer dereference.
Drop the packet if label context is not set.

    BUG: kernel NULL pointer dereference, address: 000000000000004c
    #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: 0 PID: 407 Comm: a.out Not tainted 6.4.12-arch1-1 #1 3e6fa2753a2d75925c34ecb78e22e85a65d083df
    Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 05/28/2020
    RIP: 0010:aa_label_next_confined+0xb/0x40
    Code: 00 00 48 89 ef e8 d5 25 0c 00 e9 66 ff ff ff 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 66 0f 1f 00 0f 1f 44 00 00 89 f0 <8b> 77 4c 39 c6 7e 1f 48 63 d0 48 8d 14 d7 eb 0b 83 c0 01 48 83 c2
    RSP: 0018:ffffa92940003b08 EFLAGS: 00010246
    RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000000e
    RDX: ffffa92940003be8 RSI: 0000000000000000 RDI: 0000000000000000
    RBP: ffff8b57471e7800 R08: ffff8b574c642400 R09: 0000000000000002
    R10: ffffffffbd820eeb R11: ffffffffbeb7ff00 R12: ffff8b574c642400
    R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000000
    FS:  00007fb092ea7640(0000) GS:ffff8b577bc00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 000000000000004c CR3: 00000001020f2005 CR4: 00000000007706f0
    PKRU: 55555554
    Call Trace:
     <IRQ>
     ? __die+0x23/0x70
     ? page_fault_oops+0x171/0x4e0
     ? exc_page_fault+0x7f/0x180
     ? asm_exc_page_fault+0x26/0x30
     ? aa_label_next_confined+0xb/0x40
     apparmor_secmark_check+0xec/0x330
     security_sock_rcv_skb+0x35/0x50
     sk_filter_trim_cap+0x47/0x250
     sock_queue_rcv_skb_reason+0x20/0x60
     raw_rcv+0x13c/0x210
     raw_local_deliver+0x1f3/0x250
     ip_protocol_deliver_rcu+0x4f/0x2f0
     ip_local_deliver_finish+0x76/0xa0
     __netif_receive_skb_one_core+0x89/0xa0
     netif_receive_skb+0x119/0x170
     ? __netdev_alloc_skb+0x3d/0x140
     vmxnet3_rq_rx_complete+0xb23/0x1010 [vmxnet3 56a84f9c97178c57a43a24ec073b45a9d6f01f3a]
     vmxnet3_poll_rx_only+0x36/0xb0 [vmxnet3 56a84f9c97178c57a43a24ec073b45a9d6f01f3a]
     __napi_poll+0x28/0x1b0
     net_rx_action+0x2a4/0x380
     __do_softirq+0xd1/0x2c8
     __irq_exit_rcu+0xbb/0xf0
     common_interrupt+0x86/0xa0
     </IRQ>
     <TASK>
     asm_common_interrupt+0x26/0x40
    RIP: 0010:apparmor_socket_post_create+0xb/0x200
    Code: 08 48 85 ff 75 a1 eb b1 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 0f 1f 44 00 00 41 54 <55> 48 89 fd 53 45 85 c0 0f 84 b2 00 00 00 48 8b 1d 80 56 3f 02 48
    RSP: 0018:ffffa92940ce7e50 EFLAGS: 00000286
    RAX: ffffffffbc756440 RBX: 0000000000000000 RCX: 0000000000000001
    RDX: 0000000000000003 RSI: 0000000000000002 RDI: ffff8b574eaab740
    RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
    R10: ffff8b57444cec70 R11: 0000000000000000 R12: 0000000000000003
    R13: 0000000000000002 R14: ffff8b574eaab740 R15: ffffffffbd8e4748
     ? __pfx_apparmor_socket_post_create+0x10/0x10
     security_socket_post_create+0x4b/0x80
     __sock_create+0x176/0x1f0
     __sys_socket+0x89/0x100
     __x64_sys_socket+0x17/0x20
     do_syscall_64+0x5d/0x90
     ? do_syscall_64+0x6c/0x90
     ? do_syscall_64+0x6c/0x90
     ? do_syscall_64+0x6c/0x90
     entry_SYSCALL_64_after_hwframe+0x72/0xdc

The Linux kernel CVE team has assigned CVE-2023-52889 to this issue.

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

	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 5.4.282 with commit 0abe35bc48d4
	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 5.10.224 with commit 347dcb84a487
	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 5.15.165 with commit 290a6b88e8c1
	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 6.1.103 with commit ead2ad1d9f04
	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 6.6.44 with commit 6c920754f62c
	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 6.10.3 with commit 46c17ead5b73
	Issue introduced in 4.20 with commit ab9f2115081a and fixed in 6.11 with commit fce09ea31450

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-2023-52889
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:
	security/apparmor/lsm.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/0abe35bc48d4ec80424b1f4b3560c0e082cbd5c1
	https://git.kernel.org/stable/c/347dcb84a4874b5fb375092c08d8cc4069b94f81
	https://git.kernel.org/stable/c/290a6b88e8c19b6636ed1acc733d1458206f7697
	https://git.kernel.org/stable/c/ead2ad1d9f045f26fdce3ef1644913b3a6cd38f2
	https://git.kernel.org/stable/c/6c920754f62cefc63fccdc38a062c7c3452e2961
	https://git.kernel.org/stable/c/46c17ead5b7389e22e7dc9903fd0ba865d05bda2
	https://git.kernel.org/stable/c/fce09ea314505a52f2436397608fa0a5d0934fb1