CVE-2023-53204

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

afunix: Fix data-races around user->unixinflight.

user->unixinflight is changed under spinlock(unixgclock), but toomanyunix_fds() reads it locklessly.

Let's annotate the write/read accesses to user->unix_inflight.

BUG: KCSAN: data-race in unixattachfds / unix_inflight

write to 0xffffffff8546f2d0 of 8 bytes by task 44798 on cpu 1: unixinflight+0x157/0x180 net/unix/scm.c:66 unixattachfds+0x147/0x1e0 net/unix/scm.c:123 unixscmtoskb net/unix/afunix.c:1827 [inline] unixdgramsendmsg+0x46a/0x14f0 net/unix/afunix.c:1950 unixseqpacketsendmsg net/unix/afunix.c:2308 [inline] unixseqpacketsendmsg+0xba/0x130 net/unix/afunix.c:2292 socksendmsgnosec net/socket.c:725 [inline] sock_sendmsg+0x148/0x160 net/socket.c:748 ____sys_sendmsg+0x4e4/0x610 net/socket.c:2494 ___sys_sendmsg+0xc6/0x140 net/socket.c:2548 __sys_sendmsg+0x94/0x140 net/socket.c:2577 __dosyssendmsg net/socket.c:2586 [inline] __sesyssendmsg net/socket.c:2584 [inline] __x64syssendmsg+0x45/0x50 net/socket.c:2584 dosyscallx64 arch/x86/entry/common.c:50 [inline] dosyscall64+0x3b/0x90 arch/x86/entry/common.c:80 entrySYSCALL64afterhwframe+0x6e/0xd8

read to 0xffffffff8546f2d0 of 8 bytes by task 44814 on cpu 0: toomanyunixfds net/unix/scm.c:101 [inline] unixattachfds+0x54/0x1e0 net/unix/scm.c:110 unixscmtoskb net/unix/afunix.c:1827 [inline] unixdgramsendmsg+0x46a/0x14f0 net/unix/afunix.c:1950 unixseqpacketsendmsg net/unix/afunix.c:2308 [inline] unixseqpacketsendmsg+0xba/0x130 net/unix/afunix.c:2292 socksendmsgnosec net/socket.c:725 [inline] sock_sendmsg+0x148/0x160 net/socket.c:748 ____sys_sendmsg+0x4e4/0x610 net/socket.c:2494 ___sys_sendmsg+0xc6/0x140 net/socket.c:2548 __sys_sendmsg+0x94/0x140 net/socket.c:2577 __dosyssendmsg net/socket.c:2586 [inline] __sesyssendmsg net/socket.c:2584 [inline] __x64syssendmsg+0x45/0x50 net/socket.c:2584 dosyscallx64 arch/x86/entry/common.c:50 [inline] dosyscall64+0x3b/0x90 arch/x86/entry/common.c:80 entrySYSCALL64afterhwframe+0x6e/0xd8

value changed: 0x000000000000000c -> 0x000000000000000d

Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 44814 Comm: systemd-coredum Not tainted 6.4.0-11989-g6843306689af #6 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014