CVE-2022-50073
Severity CVSS v4.0:
Pending analysis
Type:
Unavailable / Other
Publication date:
18/06/2025
Last modified:
18/06/2025
Description
In the Linux kernel, the following vulnerability has been resolved:<br />
<br />
net: tap: NULL pointer derefence in dev_parse_header_protocol when skb->dev is null<br />
<br />
Fixes a NULL pointer derefence bug triggered from tap driver.<br />
When tap_get_user calls virtio_net_hdr_to_skb the skb->dev is null<br />
(in tap.c skb->dev is set after the call to virtio_net_hdr_to_skb)<br />
virtio_net_hdr_to_skb calls dev_parse_header_protocol which<br />
needs skb->dev field to be valid.<br />
<br />
The line that trigers the bug is in dev_parse_header_protocol<br />
(dev is at offset 0x10 from skb and is stored in RAX register)<br />
if (!dev->header_ops || !dev->header_ops->parse_protocol)<br />
22e1: mov 0x10(%rbx),%rax<br />
22e5: mov 0x230(%rax),%rax<br />
<br />
Setting skb->dev before the call in tap.c fixes the issue.<br />
<br />
BUG: kernel NULL pointer dereference, address: 0000000000000230<br />
RIP: 0010:virtio_net_hdr_to_skb.constprop.0+0x335/0x410 [tap]<br />
Code: c0 0f 85 b7 fd ff ff eb d4 41 39 c6 77 cf 29 c6 48 89 df 44 01 f6 e8 7a 79 83 c1 48 85 c0 0f 85 d9 fd ff ff eb b7 48 8b 43 10 8b 80 30 02 00 00 48 85 c0 74 55 48 8b 40 28 48 85 c0 74 4c 48<br />
RSP: 0018:ffffc90005c27c38 EFLAGS: 00010246<br />
RAX: 0000000000000000 RBX: ffff888298f25300 RCX: 0000000000000010<br />
RDX: 0000000000000005 RSI: ffffc90005c27cb6 RDI: ffff888298f25300<br />
RBP: ffffc90005c27c80 R08: 00000000ffffffea R09: 00000000000007e8<br />
R10: ffff88858ec77458 R11: 0000000000000000 R12: 0000000000000001<br />
R13: 0000000000000014 R14: ffffc90005c27e08 R15: ffffc90005c27cb6<br />
FS: 0000000000000000(0000) GS:ffff88858ec40000(0000) knlGS:0000000000000000<br />
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br />
CR2: 0000000000000230 CR3: 0000000281408006 CR4: 00000000003706e0<br />
Call Trace:<br />
tap_get_user+0x3f1/0x540 [tap]<br />
tap_sendmsg+0x56/0x362 [tap]<br />
? get_tx_bufs+0xc2/0x1e0 [vhost_net]<br />
handle_tx_copy+0x114/0x670 [vhost_net]<br />
handle_tx+0xb0/0xe0 [vhost_net]<br />
handle_tx_kick+0x15/0x20 [vhost_net]<br />
vhost_worker+0x7b/0xc0 [vhost]<br />
? vhost_vring_call_reset+0x40/0x40 [vhost]<br />
kthread+0xfa/0x120<br />
? kthread_complete_and_exit+0x20/0x20<br />
ret_from_fork+0x1f/0x30