Subject: CVE-2022-48830: can: isotp: fix potential CAN frame reception race in isotp_rcv()

From: Greg Kroah-Hartman <[email-masked]>

Description
===========

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.

The Linux kernel CVE team has assigned CVE-2022-48830 to this issue.

Affected and fixed versions
===========================

	Issue introduced in 5.10 with commit e057dd3fc20f and fixed in 5.10.101 with commit 7b53d2204ce7
	Issue introduced in 5.10 with commit e057dd3fc20f and fixed in 5.15.24 with commit f90cc68f9f4b
	Issue introduced in 5.10 with commit e057dd3fc20f and fixed in 5.16.10 with commit 5b068f33bc8a
	Issue introduced in 5.10 with commit e057dd3fc20f and fixed in 5.17 with commit 7c759040c1dd

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2022-48830
will be updated if fixes are backported, please check that for the most
up to date information about this issue.

Affected files
==============

The file(s) affected by this issue are:
	net/can/isotp.c

Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/7b53d2204ce79b27a878074a77d64f40ec21dbca
	https://git.kernel.org/stable/c/f90cc68f9f4b5d8585ad5d0a206a9d37ac299ef3
	https://git.kernel.org/stable/c/5b068f33bc8acfcfd5ea7992a2dafb30d89bad30
	https://git.kernel.org/stable/c/7c759040c1dd03954f650f147ae7175476d51314