CVE-2023-53121

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 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.