CVE-2022-49018

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

mptcp: fix sleep in atomic at close time

Matt reported a splat at msk close time:

BUG: sleeping function called from invalid context at net/mptcp/protocol.c:2877
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 155, name: packetdrill
preempt_count: 201, expected: 0
RCU nest depth: 0, expected: 0
4 locks held by packetdrill/155:
#0: ffff888001536990 (&sb->s_type->i_mutex_key#6){+.+.}-{3:3}, at: __sock_release (net/socket.c:650)
#1: ffff88800b498130 (sk_lock-AF_INET){+.+.}-{0:0}, at: mptcp_close (net/mptcp/protocol.c:2973)
#2: ffff88800b49a130 (sk_lock-AF_INET/1){+.+.}-{0:0}, at: __mptcp_close_ssk (net/mptcp/protocol.c:2363)
#3: ffff88800b49a0b0 (slock-AF_INET){+...}-{2:2}, at: __lock_sock_fast (include/net/sock.h:1820)
Preemption disabled at:
0x0
CPU: 1 PID: 155 Comm: packetdrill Not tainted 6.1.0-rc5 #365
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:107 (discriminator 4))
__might_resched.cold (kernel/sched/core.c:9891)
__mptcp_destroy_sock (include/linux/kernel.h:110)
__mptcp_close (net/mptcp/protocol.c:2959)
mptcp_subflow_queue_clean (include/net/sock.h:1777)
__mptcp_close_ssk (net/mptcp/protocol.c:2363)
mptcp_destroy_common (net/mptcp/protocol.c:3170)
mptcp_destroy (include/net/sock.h:1495)
__mptcp_destroy_sock (net/mptcp/protocol.c:2886)
__mptcp_close (net/mptcp/protocol.c:2959)
mptcp_close (net/mptcp/protocol.c:2974)
inet_release (net/ipv4/af_inet.c:432)
__sock_release (net/socket.c:651)
sock_close (net/socket.c:1367)
__fput (fs/file_table.c:320)
task_work_run (kernel/task_work.c:181 (discriminator 1))
exit_to_user_mode_prepare (include/linux/resume_user_mode.h:49)
syscall_exit_to_user_mode (kernel/entry/common.c:130)
do_syscall_64 (arch/x86/entry/common.c:87)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120)

We can't call mptcp_close under the 'fast' socket lock variant, replace it with a sock_lock_nested() as the relevant code is already under the listening msk socket lock protection.

Not actual for all versions of the Red Hat Enterprise Linux. For the latest versions (where enabled) already fixed.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.