[syzbot] [wpan?] general protection fault in ieee802154_llsec_dump_table (2)

[syzbot] [wpan?] general protection fault in ieee802154_llsec_dump_table (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    c339f4010dea Merge tag 'platform-drivers-x86-v7.4-1' of gi..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=15a3dd95580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=119e5f4d0a8d39cf
dashboard link: https://syzkaller.appspot.com/bug?extid=9ea34da5ca6100593c90
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=151a448d580000

AI-generated root cause summary:
In net/ieee802154/nl-mac.c, ieee802154_llsec_dump_table() iterates through all
network devices in the namespace and assumes any device with dev->type ==
ARPHRD_IEEE802154 has a non-NULL ml_priv pointing to struct ieee802154_mlme_ops.
However, devices such as TUN can have their link type changed to
ARPHRD_IEEE802154 via the TUNSETLINK ioctl without initializing ml_priv (leaving
it NULL). Consequently, ieee802154_llsec_dump_table() dereferences
data.ops->llsec at offset 0x38 of a NULL pointer when dumping LLSEC tables,
leading to a general protection fault / kernel crash (Denial of Service).

full analysis:  https://syzkaller.appspot.com/x/ai_root_cause?x=9ea34da5ca6100593c90

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ea34da5ca6100593c90@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 0 UID: 0 PID: 6025 Comm: syz-executor400 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
RIP: 0010:ieee802154_llsec_dump_table+0x204/0x5d0 net/ieee802154/nl-mac.c:778
Code: 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 d3 02 00 00 4d 8b be b8 07 00 00 49 8d 7f 38 4c 89 bc 24 98 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 a5 02 00 00 4d 8b 7f 38 4d 85 ff 0f 84 b2 01 00
RSP: 0018:ffffc900031ef4a0 EFLAGS: 00010202
RAX: 0000000000000007 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff8880314ccb00 RSI: ffffffff8b9ff162 RDI: 0000000000000038
RBP: 0000000000000026 R08: 0000000000000324 R09: 0000000000000324
R10: ffffc900031ef40f R11: ffffc900031ef520 R12: ffff888036830610
R13: 0000000000000000 R14: ffff88805d7a8000 R15: 0000000000000000
FS:  000055558d27f400(0000) GS:ffff88812248e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff8aa5bff8 CR3: 000000002ce9b000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 genl_dumpit+0x125/0x230 net/netlink/genetlink.c:1026
 netlink_dump+0x53b/0xd00 net/netlink/af_netlink.c:2351
 __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2466
 genl_family_rcv_msg_dumpit+0x1e2/0x2e0 net/netlink/genetlink.c:1075
 genl_family_rcv_msg net/netlink/genetlink.c:1191 [inline]
 genl_rcv_msg+0x471/0x800 net/netlink/genetlink.c:1209
 netlink_rcv_skb+0x159/0x420 net/netlink/af_netlink.c:2576
 genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
 netlink_unicast_kernel net/netlink/af_netlink.c:1335 [inline]
 netlink_unicast+0x668/0x950 net/netlink/af_netlink.c:1361
 netlink_sendmsg+0x9ac/0x10c0 net/netlink/af_netlink.c:1920
 sock_sendmsg_nosec net/socket.c:800 [inline]
 __sock_sendmsg net/socket.c:818 [inline]
 __sys_sendto+0x492/0x4e0 net/socket.c:2283
 __do_sys_sendto net/socket.c:2290 [inline]
 __se_sys_sendto net/socket.c:2286 [inline]
 __x64_sys_sendto+0xe0/0x1c0 net/socket.c:2286
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0fada8d8b7
Code: 48 89 fa 4c 89 df e8 98 1d 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fff8aa5c1d0 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055558d27f400 RCX: 00007f0fada8d8b7
RDX: 0000000000000014 RSI: 00007fff8aa5c220 RDI: 0000000000000004
RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 00007f0fadac9d23
R13: 00007fff8aa5c390 R14: 000000000000001d R15: 0000000000000002
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ieee802154_llsec_dump_table+0x204/0x5d0 net/ieee802154/nl-mac.c:778
Code: 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 d3 02 00 00 4d 8b be b8 07 00 00 49 8d 7f 38 4c 89 bc 24 98 00 00 00 48 89 f8 48 c1 e8 03 <80> 3c 18 00 0f 85 a5 02 00 00 4d 8b 7f 38 4d 85 ff 0f 84 b2 01 00
RSP: 0018:ffffc900031ef4a0 EFLAGS: 00010202
RAX: 0000000000000007 RBX: dffffc0000000000 RCX: 0000000000000000
RDX: ffff8880314ccb00 RSI: ffffffff8b9ff162 RDI: 0000000000000038
RBP: 0000000000000026 R08: 0000000000000324 R09: 0000000000000324
R10: ffffc900031ef40f R11: ffffc900031ef520 R12: ffff888036830610
R13: 0000000000000000 R14: ffff88805d7a8000 R15: 0000000000000000
FS:  000055558d27f400(0000) GS:ffff88812258e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdac0fedc4 CR3: 000000002ce9b000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	89 f8                	mov    %edi,%eax
   2:	48 c1 e8 03          	shr    $0x3,%rax
   6:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
   a:	0f 85 d3 02 00 00    	jne    0x2e3
  10:	4d 8b be b8 07 00 00 	mov    0x7b8(%r14),%r15
  17:	49 8d 7f 38          	lea    0x38(%r15),%rdi
  1b:	4c 89 bc 24 98 00 00 	mov    %r15,0x98(%rsp)
  22:	00
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1) <-- trapping instruction
  2e:	0f 85 a5 02 00 00    	jne    0x2d9
  34:	4d 8b 7f 38          	mov    0x38(%r15),%r15
  38:	4d 85 ff             	test   %r15,%r15
  3b:	0f                   	.byte 0xf
  3c:	84                   	.byte 0x84
  3d:	b2 01                	mov    $0x1,%dl


---
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Forwarded: [PATCH] ieee802154: nl-mac: validate device pointers before dereference

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com.

***

Subject: [PATCH] ieee802154: nl-mac: validate device pointers before dereference
Author: skalpesh942@gmail.com

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

A virtual network device (such as a TUN interface) can have its link
type set to ARPHRD_IEEE802154 via ioctl(tun_fd, TUNSETLINK,
ARPHRD_IEEE802154). However, such devices do not have an IEEE 802.15.4
private context allocated (dev->ieee802154_ptr is NULL) and do not
register MAC operations (dev->ml_priv / ieee802154_mlme_ops(dev) is NULL).

When dumping security keys via IEEE802154_LLSEC_LIST_KEY,
ieee802154_llsec_dump_table() iterates through all net devices and
dereferences data.ops->llsec assuming that any ARPHRD_IEEE802154 device
has valid mlme ops. Because data.ops is NULL, this causes an immediate
null-pointer dereference / General Protection Fault:

  Oops: general protection fault, probably for non-canonical address
  KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
  RIP: 0010:ieee802154_llsec_dump_table+0x204/0x5d0
  Call Trace:
   <TASK>
   genl_dumpit+0x125/0x230 net/netlink/genetlink.c:1026
   netlink_dump+0x53b/0xd00 net/netlink/af_netlink.c:2351
   __netlink_dump_start+0x6d6/0x990 net/netlink/af_netlink.c:2466

Similarly, ieee802154_dump_iface() and ieee802154_nl_get_dev() assume
that ARPHRD_IEEE802154 devices have valid dev->ieee802154_ptr and
ieee802154_mlme_ops(dev) pointers.

Fix this by ensuring dev->ieee802154_ptr and ieee802154_mlme_ops(dev)
are non-NULL before proceeding in ieee802154_nl_get_dev(),
ieee802154_dump_iface(), and ieee802154_llsec_dump_table().

Fixes: 3e9c156e2c21 ("ieee802154: add netlink interfaces for llsec")
Cc: stable@vger.kernel.org
Reported-by: syzbot+9ea34da5ca6100593c90@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=9ea34da5ca6100593c90
Signed-off-by: Kalpesh Solanki <skalpesh942@gmail.com>
---
 net/ieee802154/nl-mac.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/net/ieee802154/nl-mac.c b/net/ieee802154/nl-mac.c
index 74ef0a310af..1acde5af4b5 100644
--- a/net/ieee802154/nl-mac.c
+++ b/net/ieee802154/nl-mac.c
@@ -162,7 +162,8 @@ static struct net_device *ieee802154_nl_get_dev(struct genl_info *info)
 	if (!dev)
 		return NULL;
 
-	if (dev->type != ARPHRD_IEEE802154) {
+	if (dev->type != ARPHRD_IEEE802154 || !dev->ieee802154_ptr ||
+	    !ieee802154_mlme_ops(dev)) {
 		dev_put(dev);
 		return NULL;
 	}
@@ -437,7 +438,8 @@ int ieee802154_dump_iface(struct sk_buff *skb, struct netlink_callback *cb)
 
 	idx = 0;
 	for_each_netdev(net, dev) {
-		if (idx < s_idx || dev->type != ARPHRD_IEEE802154)
+		if (idx < s_idx || dev->type != ARPHRD_IEEE802154 ||
+		    !dev->ieee802154_ptr || !ieee802154_mlme_ops(dev))
 			goto cont;
 
 		if (ieee802154_nl_fill_iface(skb, NETLINK_CB(cb->skb).portid,
@@ -771,7 +773,8 @@ ieee802154_llsec_dump_table(struct sk_buff *skb, struct netlink_callback *cb,
 	int rc;
 
 	for_each_netdev(net, dev) {
-		if (idx < first_dev || dev->type != ARPHRD_IEEE802154)
+		if (idx < first_dev || dev->type != ARPHRD_IEEE802154 ||
+		    !dev->ieee802154_ptr || !ieee802154_mlme_ops(dev))
 			goto skip;
 
 		data.ops = ieee802154_mlme_ops(dev);
--