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| author | Tristan Hume <tristan@thume.ca> | 2022-01-27 17:08:06 -0500 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-02-02 13:11:40 +0100 |
| commit | 1d9093457b243061a9bba23543c38726e864a643 (patch) | |
| tree | 614f8cd4fe5fe58686035bedad67d331b5f492dc /arch/x86 | |
| parent | ddecd22878601a606d160680fa85802b75d92eb6 (diff) | |
| download | linux-1d9093457b243061a9bba23543c38726e864a643.tar.bz2 | |
perf/x86/intel/pt: Fix crash with stop filters in single-range mode
Add a check for !buf->single before calling pt_buffer_region_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 pt_handle_status due to calling
pt_buffer_region_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.
Fixes: 670638477aed ("perf/x86/intel/pt: Opportunistically use single range output mode")
Signed-off-by: Tristan Hume <tristan@thume.ca>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20220127220806.73664-1-tristan@thume.ca
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/events/intel/pt.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index 7f406c14715f..2d33bba9a144 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -897,8 +897,9 @@ static void pt_handle_status(struct pt *pt) * means we are already losing data; need to let the decoder * know. */ - if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) || - buf->output_off == pt_buffer_region_size(buf)) { + if (!buf->single && + (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) || + buf->output_off == pt_buffer_region_size(buf))) { perf_aux_output_flag(&pt->handle, PERF_AUX_FLAG_TRUNCATED); advance++; |