From: Xiao Liang <shaw.leon@gmail.com>
To: linux-security-module@vger.kernel.org
Cc: John Johansen <john.johansen@canonical.com>,
Matthew Garrett <mjg59@google.com>
Subject: [PATCH] apparmor: Fix null pointer deref when receiving skb during sock creation
Date: Sat, 2 Sep 2023 08:48:38 +0800 [thread overview]
Message-ID: <20230902004841.614102-1-shaw.leon@gmail.com> (raw)
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
Fixes: ab9f2115081a ("apparmor: Allow filtering based on secmark policy")
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
---
security/apparmor/lsm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 108eccc5ada5..0dbff677ac2e 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -1097,6 +1097,13 @@ static int apparmor_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
if (!skb->secmark)
return 0;
+ /*
+ * If reach here before socket_post_create hook is called, in which
+ * case label is null, drop the packet.
+ */
+ if (!ctx->label)
+ return -EACCES;
+
return apparmor_secmark_check(ctx->label, OP_RECVMSG, AA_MAY_RECEIVE,
skb->secmark, sk);
}
--
2.42.0
next reply other threads:[~2023-09-02 0:48 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-02 0:48 Xiao Liang [this message]
2023-10-16 3:36 ` [PATCH] apparmor: Fix null pointer deref when receiving skb during sock creation John Johansen
2024-01-23 6:16 ` Xiao Liang
2024-01-27 8:20 ` John Johansen
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