CVE-2023-53121: tcp: tcp_make_synack() can be called from process context

CVE-2023-53121: tcp: tcp_make_synack() can be called from process context

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

tcp: tcp_make_synack() can be called from process context

tcp_rtx_synack() now could be called in process context as explained in
0a375c822497 ("tcp: tcp_rtx_synack() can be called from process
context").

tcp_rtx_synack() might call tcp_make_synack(), which will touch per-CPU
variables with preemption enabled. This causes the following BUG:

    BUG: using __this_cpu_add() in preemptible [00000000] code: ThriftIO1/5464
    caller is tcp_make_synack+0x841/0xac0
    Call Trace:
     <TASK>
     dump_stack_lvl+0x10d/0x1a0
     check_preemption_disabled+0x104/0x110
     tcp_make_synack+0x841/0xac0
     tcp_v6_send_synack+0x5c/0x450
     tcp_rtx_synack+0xeb/0x1f0
     inet_rtx_syn_ack+0x34/0x60
     tcp_check_req+0x3af/0x9e0
     tcp_rcv_state_process+0x59b/0x2030
     tcp_v6_do_rcv+0x5f5/0x700
     release_sock+0x3a/0xf0
     tcp_sendmsg+0x33/0x40
     ____sys_sendmsg+0x2f2/0x490
     __sys_sendmsg+0x184/0x230
     do_syscall_64+0x3d/0x90

Avoid calling __TCP_INC_STATS() with will touch per-cpu variables. Use
TCP_INC_STATS() which is safe to be called from context switch.

The Linux kernel CVE team has assigned CVE-2023-53121 to this issue.


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

	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 4.14.311 with commit d493d4fe88195a144d6a277a90062a7534ed2192
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 4.19.279 with commit e23ca307745be3df7fe9762f3e2a7e311a57852e
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 5.4.238 with commit 442aa78ed70188b21ccd8669738448702c0a3281
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 5.10.176 with commit 77ad58bca0119e8cc3e0e9d91a3f22caa66e4dfa
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 5.15.104 with commit ad07290d63ff6689f50565b02f5b6f34ec15a5ca
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 6.1.21 with commit 9180aa4622a720b433e842b4d3aa34d73eec577a
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 6.2.8 with commit 7613cde8c0c1f02a7ec2e1d536c01b65b135fc1c
	Issue introduced in 3.7 with commit 8336886f786fdacbc19b719c1f7ea91eb70706d4 and fixed in 6.3 with commit bced3f7db95ff2e6ca29dc4d1c9751ab5e736a09

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-2023-53121
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/ipv4/tcp_output.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/d493d4fe88195a144d6a277a90062a7534ed2192
	https://git.kernel.org/stable/c/e23ca307745be3df7fe9762f3e2a7e311a57852e
	https://git.kernel.org/stable/c/442aa78ed70188b21ccd8669738448702c0a3281
	https://git.kernel.org/stable/c/77ad58bca0119e8cc3e0e9d91a3f22caa66e4dfa
	https://git.kernel.org/stable/c/ad07290d63ff6689f50565b02f5b6f34ec15a5ca
	https://git.kernel.org/stable/c/9180aa4622a720b433e842b4d3aa34d73eec577a
	https://git.kernel.org/stable/c/7613cde8c0c1f02a7ec2e1d536c01b65b135fc1c
	https://git.kernel.org/stable/c/bced3f7db95ff2e6ca29dc4d1c9751ab5e736a09