CVE-2023-54006

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

afunix: Fix data-race around unixtot_inflight.

unixtotinflight is changed under spinlock(unixgclock), but unixrelease_sock() reads it locklessly.

Let's use READONCE() for unixtot_inflight.

Note that the writer side was marked by commit 9d6d7f1cb67c ("afunix: annote lockless accesses to unixtotinflight & gcin_progress")

BUG: KCSAN: data-race in unixinflight / unixrelease_sock

write (marked) to 0xffffffff871852b8 of 4 bytes by task 123 on cpu 1: unixinflight+0x130/0x180 net/unix/scm.c:64 unixattachfds+0x137/0x1b0 net/unix/scm.c:123 unixscmtoskb net/unix/afunix.c:1832 [inline] unixdgramsendmsg+0x46a/0x14f0 net/unix/afunix.c:1955 socksendmsgnosec net/socket.c:724 [inline] sock_sendmsg+0x148/0x160 net/socket.c:747 ____sys_sendmsg+0x4e4/0x610 net/socket.c:2493 ___sys_sendmsg+0xc6/0x140 net/socket.c:2547 __sys_sendmsg+0x94/0x140 net/socket.c:2576 __dosyssendmsg net/socket.c:2585 [inline] __sesyssendmsg net/socket.c:2583 [inline] __x64syssendmsg+0x45/0x50 net/socket.c:2583 dosyscallx64 arch/x86/entry/common.c:50 [inline] dosyscall64+0x3b/0x90 arch/x86/entry/common.c:80 entrySYSCALL64afterhwframe+0x72/0xdc

read to 0xffffffff871852b8 of 4 bytes by task 4891 on cpu 0: unixreleasesock+0x608/0x910 net/unix/afunix.c:671 unixrelease+0x59/0x80 net/unix/af_unix.c:1058 __sockrelease+0x7d/0x170 net/socket.c:653 sockclose+0x19/0x30 net/socket.c:1385 __fput+0x179/0x5e0 fs/file_table.c:321 ____fput+0x15/0x20 fs/filetable.c:349 taskworkrun+0x116/0x1a0 kernel/taskwork.c:179 resumeusermode_work include/linux/resumeusermode.h:49 [inline] exittousermodeloop kernel/entry/common.c:171 [inline] exittousermodeprepare+0x174/0x180 kernel/entry/common.c:204 _syscallexittousermodework kernel/entry/common.c:286 [inline] syscallexittousermode+0x1a/0x30 kernel/entry/common.c:297 dosyscall64+0x4b/0x90 arch/x86/entry/common.c:86 entrySYSCALL64afterhwframe+0x72/0xdc

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 4891 Comm: systemd-coredum Not tainted 6.4.0-rc5-01219-gfa0e21fa4443 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014