CVE-2022-48830

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

can: isotp: fix potential CAN frame reception race in isotp_rcv()

When receiving a CAN frame the current code logic does not consider

concurrently receiving processes which do not show up in real world

usage.

Ziyang Xuan writes:

The following syz problem is one of the scenarios. so->rx.len is

changed by isotp_rcv_ff() during isotp_rcv_cf(), so->rx.len equals

0 before alloc_skb() and equals 4096 after alloc_skb(). That will

trigger skb_over_panic() in skb_put().

=======================================================

CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc8-syzkaller #0

RIP: 0010:skb_panic+0x16c/0x16e net/core/skbuff.c:113

Call Trace:

<TASK>

skb_over_panic net/core/skbuff.c:118 [inline]

skb_put.cold+0x24/0x24 net/core/skbuff.c:1990

isotp_rcv_cf net/can/isotp.c:570 [inline]

isotp_rcv+0xa38/0x1e30 net/can/isotp.c:668

deliver net/can/af_can.c:574 [inline]

can_rcv_filter+0x445/0x8d0 net/can/af_can.c:635

can_receive+0x31d/0x580 net/can/af_can.c:665

can_rcv+0x120/0x1c0 net/can/af_can.c:696

__netif_receive_skb_one_core+0x114/0x180 net/core/dev.c:5465

__netif_receive_skb+0x24/0x1b0 net/core/dev.c:5579

Therefore we make sure the state changes and data structures stay

consistent at CAN frame reception time by adding a spin_lock in

isotp_rcv(). This fixes the issue reported by syzkaller but does not

affect real world operation.