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Message-ID: <ZfLKjD6aMrGPEgHh@zeus>
Date: Thu, 14 Mar 2024 18:59:40 +0900
From: Ryosuke Yasuoka <ryasuoka@...hat.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
pabeni@...hat.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, syoshida@...hat.com,
syzbot+7ea9413ea6749baf5574@...kaller.appspotmail.com
Subject: Re: [PATCH net] nfc: nci: Fix uninit-value in nci_dev_up
On Wed, Mar 13, 2024 at 10:01:27AM +0100, Krzysztof Kozlowski wrote:
> On 12/03/2024 15:56, Ryosuke Yasuoka wrote:
> > syzbot reported the following unitit-value access issue [1]:
>
> If there is going to be any new version then: typo, uninit-value
Thank you for pointing out. I'll fix it.
> >
> > nci_ntf_packet() calls each ntf operation parsed from skb->data. When
> > the payload length is zero, each operation handler reads uninitialized
> > payload and KMSAN detects this issue. Such notification packet should be
> > silently discarded since it is unexpected for any notification handlers.
> >
> > This patch resolved this issue by checking payload size before calling
> > each notification handler codes.
> >
> > BUG: KMSAN: uninit-value in nci_init_req net/nfc/nci/core.c:177 [inline]
> > BUG: KMSAN: uninit-value in __nci_request net/nfc/nci/core.c:108 [inline]
> > BUG: KMSAN: uninit-value in nci_open_device net/nfc/nci/core.c:521 [inline]
> > BUG: KMSAN: uninit-value in nci_dev_up+0xfec/0x1b10 net/nfc/nci/core.c:632
> > nci_init_req net/nfc/nci/core.c:177 [inline]
> > __nci_request net/nfc/nci/core.c:108 [inline]
> > nci_open_device net/nfc/nci/core.c:521 [inline]
> > nci_dev_up+0xfec/0x1b10 net/nfc/nci/core.c:632
> > nfc_dev_up+0x26e/0x440 net/nfc/core.c:118
> > nfc_genl_dev_up+0xfe/0x1d0 net/nfc/netlink.c:770
> > genl_family_rcv_msg_doit net/netlink/genetlink.c:972 [inline]
> > genl_family_rcv_msg net/netlink/genetlink.c:1052 [inline]
> > genl_rcv_msg+0x11ec/0x1290 net/netlink/genetlink.c:1067
> > netlink_rcv_skb+0x371/0x650 net/netlink/af_netlink.c:2545
> > genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076
> > netlink_unicast_kernel net/netlink/af_netlink.c:1342 [inline]
> > netlink_unicast+0xf47/0x1250 net/netlink/af_netlink.c:1368
> > netlink_sendmsg+0x1238/0x13d0 net/netlink/af_netlink.c:1910
> > sock_sendmsg_nosec net/socket.c:730 [inline]
> > __sock_sendmsg net/socket.c:745 [inline]
> > ____sys_sendmsg+0x9c2/0xd60 net/socket.c:2584
> > ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2638
> > __sys_sendmsg net/socket.c:2667 [inline]
> > __do_sys_sendmsg net/socket.c:2676 [inline]
> > __se_sys_sendmsg net/socket.c:2674 [inline]
> > __x64_sys_sendmsg+0x307/0x490 net/socket.c:2674
> > do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> > do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
> > entry_SYSCALL_64_after_hwframe+0x63/0x6b
> >
> > Uninit was stored to memory at:
> > nci_core_reset_ntf_packet net/nfc/nci/ntf.c:36 [inline]
> > nci_ntf_packet+0x19dc/0x39c0 net/nfc/nci/ntf.c:782
> > nci_rx_work+0x213/0x500 net/nfc/nci/core.c:1522
> > process_one_work kernel/workqueue.c:2633 [inline]
> > process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2706
> > worker_thread+0xf45/0x1490 kernel/workqueue.c:2787
> > kthread+0x3ed/0x540 kernel/kthread.c:388
> > ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
> > ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
> >
> > Uninit was created at:
> > slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768
> > slab_alloc_node mm/slub.c:3478 [inline]
> > kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523
> > kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560
> > __alloc_skb+0x318/0x740 net/core/skbuff.c:651
> > alloc_skb include/linux/skbuff.h:1286 [inline]
> > virtual_ncidev_write+0x6d/0x280 drivers/nfc/virtual_ncidev.c:120
> > vfs_write+0x48b/0x1200 fs/read_write.c:588
> > ksys_write+0x20f/0x4c0 fs/read_write.c:643
> > __do_sys_write fs/read_write.c:655 [inline]
> > __se_sys_write fs/read_write.c:652 [inline]
> > __x64_sys_write+0x93/0xd0 fs/read_write.c:652
> > do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> > do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
> > entry_SYSCALL_64_after_hwframe+0x63/0x6b
> >
> > CPU: 1 PID: 5012 Comm: syz-executor935 Not tainted 6.7.0-syzkaller-00562-g9f8413c4a66f #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
>
> These two lines are not really relevant, it's a virtual platform, so
> whether this is Google or Amazon it does not matter, and your log paste
> is already quite long. If there is going to be any resend, I propose to
> drop.
OK. Do you mean all these log messages that syzbot reported should be
dropped or I should leave only relavant messages?
> >
> > Fixes: 6a2968aaf50c ("NFC: basic NCI protocol implementation")
> > Reported-and-tested-by: syzbot+7ea9413ea6749baf5574@...kaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=7ea9413ea6749baf5574 [1]
> > Signed-off-by: Ryosuke Yasuoka <ryasuoka@...hat.com>
> > ---
> > net/nfc/nci/ntf.c | 3 +++
> > 1 file changed, 3 insertions(+)
> >
> > diff --git a/net/nfc/nci/ntf.c b/net/nfc/nci/ntf.c
> > index 994a0a1efb58..56624387e253 100644
> > --- a/net/nfc/nci/ntf.c
> > +++ b/net/nfc/nci/ntf.c
> > @@ -765,6 +765,9 @@ void nci_ntf_packet(struct nci_dev *ndev, struct sk_buff *skb)
> > nci_opcode_oid(ntf_opcode),
> > nci_plen(skb->data));
> >
> > + if (!nci_plen(skb->data))
> > + goto end;
>
> Looks reasonable, however wouldn't there be the same issue in
> nci_rsp_packet() and other cases from nci_rx_work()? I wonder why only
> NTF packets could be constructed without payload.
Yes, I can reproduced very similar bug reported by syzbot [2] in my lab.
When the MT is NCI_MT_RSP_PKT (0x2), KMSAN detects the following bug in
nci_rsp_packet().
[How to reproduce]
(gdb) b net/nfc/nci/core.c:1516
Breakpoint 2 at 0xffffffff8eba68bc: file net/nfc/nci/core.c, line 1516.
(gdb) c <<<--- Run the reproducer provided in [1]
...
1516 switch (nci_mt(skb->data)) {
(gdb) p skb->data
$2 = (unsigned char *) 0xffff88802e75d400 "`"
(gdb) p/x *(unsigned char *)0xffff88802e75d400
$4 = 0x60
(gdb) p/x *(unsigned char *)0xffff88802e75d400 = 0x50
$5 = 0x50
(gdb) c
...
[ 370.186593][ T8135] =====================================================
[ 370.188107][ T8135] BUG: KMSAN: uninit-value in nci_dev_up+0xfb4/0x1590
[ 370.189016][ T8135] nci_dev_up+0xfb4/0x1590
[ 370.189642][ T8135] nfc_dev_up+0x281/0x520
[ 370.190312][ T8135] nfc_genl_dev_up+0xf1/0x1c0
[ 370.190990][ T8135] genl_rcv_msg+0x1220/0x12c0
[ 370.192189][ T8135] netlink_rcv_skb+0x542/0x670
[ 370.192865][ T8135] genl_rcv+0x41/0x60
[ 370.193426][ T8135] netlink_unicast+0xf43/0x1220
[ 370.194118][ T8135] netlink_sendmsg+0x1242/0x1420
[ 370.194801][ T8135] ____sys_sendmsg+0x98b/0xd10
[ 370.195509][ T8135] ___sys_sendmsg+0x271/0x3b0
[ 370.196163][ T8135] __x64_sys_sendmsg+0x2ee/0x4b0
[ 370.196849][ T8135] do_syscall_64+0x6d/0x140
[ 370.197511][ T8135] entry_SYSCALL_64_after_hwframe+0x63/0x6b
[ 370.198362][ T8135]
[ 370.198681][ T8135] Uninit was stored to memory at:
[ 370.199392][ T8135] nci_dev_up+0xfad/0x1590
[ 370.200011][ T8135] nfc_dev_up+0x281/0x520
[ 370.200608][ T8135] nfc_genl_dev_up+0xf1/0x1c0
[ 370.201669][ T8135] genl_rcv_msg+0x1220/0x12c0
[ 370.202332][ T8135] netlink_rcv_skb+0x542/0x670
[ 370.203012][ T8135] genl_rcv+0x41/0x60
[ 370.203563][ T8135] netlink_unicast+0xf43/0x1220
[ 370.204250][ T8135] netlink_sendmsg+0x1242/0x1420
[ 370.204914][ T8135] ____sys_sendmsg+0x98b/0xd10
[ 370.205525][ T8135] ___sys_sendmsg+0x271/0x3b0
[ 370.206041][ T8135] __x64_sys_sendmsg+0x2ee/0x4b0
[ 370.206552][ T8135] do_syscall_64+0x6d/0x140
[ 370.207106][ T8135] entry_SYSCALL_64_after_hwframe+0x63/0x6b
[ 370.207841][ T8135]
[ 370.208160][ T8135] Uninit was stored to memory at:
[ 370.208749][ T8135] nci_rsp_packet+0x1daf/0x3b30
[ 370.209295][ T8135] nci_rx_work+0x1e8/0x530
[ 370.209746][ T8135] process_scheduled_works+0x1174/0x1e20
[ 370.210449][ T8135] worker_thread+0xea3/0x1490
[ 370.210989][ T8135] kthread+0x3d1/0x530
[ 370.211932][ T8135] ret_from_fork+0x66/0x80
[ 370.212580][ T8135] ret_from_fork_asm+0x11/0x20
345 void nci_rsp_packet(struct nci_dev *ndev, struct sk_buff *skb)
346 {
347 __u16 rsp_opcode = nci_opcode(skb->data);
...
370 switch (rsp_opcode) {
371 case NCI_OP_CORE_RESET_RSP:
372 nci_core_reset_rsp_packet(ndev, skb);
28 static void nci_core_reset_rsp_packet(struct nci_dev *ndev,
29 const struct sk_buff *skb)
30 {
31 const struct nci_core_reset_rsp *rsp = (void *)skb->data;
...
36 if (skb->len != 1) {
37 if (rsp->status == NCI_STATUS_OK) {
38 ndev->nci_ver = rsp->nci_ver; <<<---
So it means we should check the payload length in not nci_ntf_packet()
but in nci_rx_work(). Like this. (Note that it has not tested.)
diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index 6c9592d05120..f9880d6ad2b2 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1512,6 +1512,11 @@ static void nci_rx_work(struct work_struct *work)
nfc_send_to_raw_sock(ndev->nfc_dev, skb,
RAW_PAYLOAD_NCI, NFC_DIRECTION_RX);
+ if (!nci_plen(skb->data)) {
+ skb(free);
+ break;
+ }
+
/* Process frame */
switch (nci_mt(skb->data)) {
case NCI_MT_RSP_PKT:
Let me know if you have any idea.
https://syzkaller.appspot.com/bug?extid=7ea9413ea6749baf5574 [1]
https://syzkaller.appspot.com/bug?extid=685805de744584f4d24b [2]
Best Regards,
Ryosuke
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