CVE-2025-71125

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

tracing: Do not register unsupported perf events

Synthetic events currently do not have a function to register perf events.

This leads to calling the tracepoint register functions with a NULL

function pointer which triggers:

------------[ cut here ]------------

WARNING: kernel/tracepoint.c:175 at tracepoint_add_func+0x357/0x370, CPU#2: perf/2272

Modules linked in: kvm_intel kvm irqbypass

CPU: 2 UID: 0 PID: 2272 Comm: perf Not tainted 6.18.0-ftest-11964-ge022764176fc-dirty #323 PREEMPTLAZY

Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.17.0-debian-1.17.0-1 04/01/2014

RIP: 0010:tracepoint_add_func+0x357/0x370

Code: 28 9c e8 4c 0b f5 ff eb 0f 4c 89 f7 48 c7 c6 80 4d 28 9c e8 ab 89 f4 ff 31 c0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc <0f> 0b 49 c7 c6 ea ff ff ff e9 ee fe ff ff 0f 0b e9 f9 fe ff ff 0f

RSP: 0018:ffffabc0c44d3c40 EFLAGS: 00010246

RAX: 0000000000000001 RBX: ffff9380aa9e4060 RCX: 0000000000000000

RDX: 000000000000000a RSI: ffffffff9e1d4a98 RDI: ffff937fcf5fd6c8

RBP: 0000000000000001 R08: 0000000000000007 R09: ffff937fcf5fc780

R10: 0000000000000003 R11: ffffffff9c193910 R12: 000000000000000a

R13: ffffffff9e1e5888 R14: 0000000000000000 R15: ffffabc0c44d3c78

FS: 00007f6202f5f340(0000) GS:ffff93819f00f000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 000055d3162281a8 CR3: 0000000106a56003 CR4: 0000000000172ef0

Call Trace:

<TASK>

tracepoint_probe_register+0x5d/0x90

synth_event_reg+0x3c/0x60

perf_trace_event_init+0x204/0x340

perf_trace_init+0x85/0xd0

perf_tp_event_init+0x2e/0x50

perf_try_init_event+0x6f/0x230

? perf_event_alloc+0x4bb/0xdc0

perf_event_alloc+0x65a/0xdc0

__se_sys_perf_event_open+0x290/0x9f0

do_syscall_64+0x93/0x7b0

? entry_SYSCALL_64_after_hwframe+0x76/0x7e

? trace_hardirqs_off+0x53/0xc0

entry_SYSCALL_64_after_hwframe+0x76/0x7e

Instead, have the code return -ENODEV, which doesn't warn and has perf

error out with:

# perf record -e synthetic:futex_wait

Error:

The sys_perf_event_open() syscall returned with 19 (No such device) for event (synthetic:futex_wait).

"dmesg | grep -i perf" may provide additional information.

Ideally perf should support synthetic events, but for now just fix the

warning. The support can come later.