CVE-2022-48713

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

perf/x86/intel/pt: Fix crash with stop filters in single-range mode

Add a check for !buf->single before calling ptbufferregion_size in a place where a missing check can cause a kernel crash.

Fixes a bug introduced by commit 670638477aed ("perf/x86/intel/pt: Opportunistically use single range output mode"), which added a support for PT single-range output mode. Since that commit if a PT stop filter range is hit while tracing, the kernel will crash because of a null pointer dereference in pthandlestatus due to calling ptbufferregion_size without a ToPA configured.

The commit which introduced single-range mode guarded almost all uses of the ToPA buffer variables with checks of the buf->single variable, but missed the case where tracing was stopped by the PT hardware, which happens when execution hits a configured stop filter.

Tested that hitting a stop filter while PT recording successfully records a trace with this patch but crashes without this patch.