bpf: Wait for an RCU tasks grace period before freeing trampoline progs

Summary

In the Linux kernel, the following vulnerability has been resolved: bpf: Wait for an RCU tasks grace period before freeing trampoline progs When a prog is detached from a trampoline, it is freed after an RCU grace period, or an RCU tasks trace one if it is sleepable. This covers the tasks that are running the prog, since the prog's enter helper takes the matching read lock before the prog is called. On a preemptible kernel, it doesn't cover a task that was preempted in the trampoline just before the enter helper. That task holds no lock yet, and it calls the prog after it was freed: BUG: KASAN: vmalloc-out-of-bounds in __bpf_prog_enter_recur+0x3a5/0x3f0 Read of size 8 at addr ffffc90000055040 by task candidate/110 CPU: 1 UID: 0 PID: 110 Comm: candidate Not tainted 7.3.0-rc2-00014-g15071f2a1263-dirty #2 PREEMPT(full) Call Trace: <TASK> __bpf_prog_enter_recur+0x3a5/0x3f0 bpf_trampoline_6442509193+0x37/0xf1 __x64_sys_futex+0x9/0x410 do_syscall_64+0xb0/0x530 ... Wait for an RCU tasks grace period before the existing one when freeing a prog that was linked to a trampoline. An RCU tasks grace period only ends once the tasks that were preempted have run again, and bpf_tramp_image_put() already relies on it to free the image. It doesn't wait for tasks that sleep in the trampoline, the next commit takes care of those. Only progs that were linked to a trampoline can be called this way, so bpf_trampoline_add_prog() marks them and other progs are still freed as before.

Timeline

1. Oct 18, 2026, 3:48 PM UTCCVE published
2. Oct 19, 2026, 9:25 AM UTCRecord last updated

Affected versions

• Linux Linux

  From e21aa341785c679dd409c8cb71f864c00fe6c463 · fixed in 40955f6512a03f0e046f5256b0706b26ba191018; From e21aa341785c679dd409c8cb71f864c00fe6c463 · fixed in 0fb5751a6e411b1b466c06e50021818d9391df98; From 5.10.28 · fixed in 5.11; From 5.11.11 · fixed in 5.12

• Linux Linux

  5.12

• KernelLinux

  From 5.12.0 · fixed in 7.2.10

References 2