In the Linux kernel, the following vulnerability has been resolved:
perf: Require kernel access for text poke events
Perf events with exclude_kernel=1 can be opened without kernel perf
access. However, exclude_kernel does not suppress text-poke sideband
records. Every PERF_RECORD_TEXT_POKE is marked PERF_RECORD_MISC_KERNEL
and contains a raw kernel instruction address.
An unprivileged task can therefore open and mmap a task-local software
event with text_poke=1. Both opening a count-only tracepoint event and
configuring UDP GRO for ESP-in-UDP cause updates to inline static calls;
the observer receives the relocated addresses of the modified instructions.
For a known kernel image, any such address reveals the runtime kernel
text base despite KASLR.
Call perf_allow_kernel() whenever attr.text_poke is set, regardless of
exclude_kernel. Events that neither monitor kernel execution nor request
text-poke records retain their existing permissions.
