Kernel Tracepoint regfunc() not undone on func_add() failure
CVE-2026-46196 Published on May 28, 2026
tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func()
In the Linux kernel, the following vulnerability has been resolved:
tracepoint: balance regfunc() on func_add() failure in tracepoint_add_func()
When a tracepoint goes through the 0 -> 1 transition, tracepoint_add_func()
invokes the subsystem's ext->regfunc() before attempting to install the
new probe via func_add(). If func_add() then fails (for example, when
allocate_probes() cannot allocate a new probe array under memory pressure
and returns -ENOMEM), the function returns the error without calling the
matching ext->unregfunc(), leaving the side effects of regfunc() behind
with no installed probe to justify them.
For syscall tracepoints this is particularly unpleasant: syscall_regfunc()
bumps sys_tracepoint_refcount and sets SYSCALL_TRACEPOINT on every task.
After a leaked failure, the refcount is stuck at a non-zero value with no
consumer, and every task continues paying the syscall trace entry/exit
overhead until reboot. Other subsystems providing regfunc()/unregfunc()
pairs exhibit similarly scoped persistent state.
Mirror the existing 1 -> 0 cleanup and call ext->unregfunc() in the
func_add() error path, gated on the same condition used there so the
unwind is symmetric with the registration.
Products Associated with CVE-2026-46196
Want to know whenever a new CVE is published for Linux Kernel? stack.watch will email you.
Affected Versions
Linux:- Version 8cf868affdc459beee1a941df0cfaba1673740e3 and below 247ed8a969f981bfba3112fd4bb441eaa6cef59c is affected.
- Version 8cf868affdc459beee1a941df0cfaba1673740e3 and below 7bcadb3c2bc1cf60690e931aadd35fb7bd646a49 is affected.
- Version 8cf868affdc459beee1a941df0cfaba1673740e3 and below 2c5b8eeea006eb694c81631cd5713d494b80be90 is affected.
- Version 8cf868affdc459beee1a941df0cfaba1673740e3 and below 342829e042ac00f3d68d442ea92873fb6683f494 is affected.
- Version 8cf868affdc459beee1a941df0cfaba1673740e3 and below fad217e16fded7f3c09f8637b0f6a224d58b5f2e is affected.
- Version 4.10 is affected.
- Before 4.10 is unaffected.
- Version 6.6.140, <= 6.6.* is unaffected.
- Version 6.12.88, <= 6.12.* is unaffected.
- Version 6.18.30, <= 6.18.* is unaffected.
- Version 7.0.7, <= 7.0.* is unaffected.
- Version 7.1-rc1, <= * is unaffected.