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perf/x86/amd/ibs: Don't access non-started event
[ Upstream commit d2753e6b48
]
Paul Menzel reported the following bug:
> Enabling the undefined behavior sanitizer and building GNU/Linux 4.18-rc5+
> (with some unrelated commits) with GCC 8.1.0 from Debian Sid/unstable, the
> warning below is shown.
>
> > [ 2.111913]
> > ================================================================================
> > [ 2.111917] UBSAN: Undefined behaviour in arch/x86/events/amd/ibs.c:582:24
> > [ 2.111919] member access within null pointer of type 'struct perf_event'
> > [ 2.111926] CPU: 0 PID: 144 Comm: udevadm Not tainted 4.18.0-rc5-00316-g4864b68cedf2 #104
> > [ 2.111928] Hardware name: ASROCK E350M1/E350M1, BIOS TIMELESS 01/01/1970
> > [ 2.111930] Call Trace:
> > [ 2.111943] dump_stack+0x55/0x89
> > [ 2.111949] ubsan_epilogue+0xb/0x33
> > [ 2.111953] handle_null_ptr_deref+0x7f/0x90
> > [ 2.111958] __ubsan_handle_type_mismatch_v1+0x55/0x60
> > [ 2.111964] perf_ibs_handle_irq+0x596/0x620
The code dereferences event before checking the STARTED bit. Patch
below should cure the issue.
The warning should not trigger, if I analyzed the thing correctly.
(And Paul's testing confirms this.)
Reported-by: Paul Menzel <pmenzel@molgen.mpg.de>
Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Menzel <pmenzel+linux-x86@molgen.mpg.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1807200958390.1580@nanos.tec.linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
parent
c5d7e5e83b
commit
b3c2509872
1 changed files with 5 additions and 1 deletions
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@ -578,7 +578,7 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
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{
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struct cpu_perf_ibs *pcpu = this_cpu_ptr(perf_ibs->pcpu);
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struct perf_event *event = pcpu->event;
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struct hw_perf_event *hwc = &event->hw;
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struct hw_perf_event *hwc;
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struct perf_sample_data data;
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struct perf_raw_record raw;
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struct pt_regs regs;
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@ -601,6 +601,10 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs)
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return 0;
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}
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if (WARN_ON_ONCE(!event))
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goto fail;
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hwc = &event->hw;
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msr = hwc->config_base;
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buf = ibs_data.regs;
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rdmsrl(msr, *buf);
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