Re: [PATCH 1/2] libtraceevent: Add eof checks.

[Steven Rostedt <rostedt@goodmis.org>]

On Thu, 17 Jun 2021 15:58:28 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> On Thu, 17 Jun 2021 19:43:25 +0000
> Claire Jensen <cjense@google.com> wrote:
> 
> Hi Claire,
> 
> Thanks for sending the patches, I'll try to get some time to look at them
> (note, that I have a lot of other duties that I need to finish before I can
> get to this).
> 
> > Added checking for __read_char and peek_char to make sure value is not at end
> > of file.
> > 
> > This issue was found while fuzz testing. One of the test cases created an infinite loop because __read_token had reached end of file. Checking was added to all cases where this may occur.  
> 
> You don't need to fix this now, but for future reference, we follow the
> Linux guidelines on submitting patches which includes having line breaks at
> 74 (although I use 76) bytes, for the change log.
> 
> This makes the change logs easier to read.
> 

I made the mistake of adding this patch and pushing it to a new release
without running my test suite against it. It ended up breaking the parsing.

When running with --debug -N, I get:

  [ftrace:branch] unexpected type 1
  [sched:sched_switch] unknown op ''
  [irq:irq_handler_exit] unexpected type 1
  [timer:timer_start] unknown op ''
  [kvm:vcpu_match_mmio] unexpected type 1
  [kvm:kvm_wait_lapic_expire] unknown op ''
  [kvm:kvm_vcpu_wakeup] unexpected type 1
  [kvm:kvm_userspace_exit] unknown op ''
  [kvm:kvm_pv_tlb_flush] unexpected type 1
  [kvm:kvm_ple_window_update] unknown op ''
  [kvm:kvm_pio] unknown op ''
  [kvm:kvm_pic_set_irq] unknown op ''
  [kvm:kvm_nested_vmrun] unexpected type 1
  [kvm:kvm_nested_vmexit_inject] unknown op ''
  Error: expected type 5 but read 0
  [kvm:kvm_nested_vmexit] unknown op ''
  Error: expected type 5 but read 0
  [kvm:kvm_nested_vmenter_failed] bad op token 
  [kvm:kvm_msr] unexpected type 1
  [kvm:kvm_msi_set_irq] unknown op ''
  unknown op ''
  [kvm:kvm_ioapic_set_irq] unknown op ''
  Error: expected type 5 but read 0
  unknown op ''
  [kvm:kvm_ioapic_delayed_eoi_inj] unknown op ''
  Error: expected type 5 but read 0
  [kvm:kvm_exit] unknown op ''
  Error: expected type 5 but read 0
  [kvm:kvm_emulate_insn] unknown op ''
  Error: expected type 5 but read 0
  [kvm:kvm_cpuid] unexpected type 1
  unknown op ''
  [kvm:kvm_apic_ipi] unknown op ''
  Error: expected type 5 but read 0
  unknown op ''
  [kvm:kvm_apic_accept_irq] unknown op ''
  Error: expected type 5 but read 0
  [kvm:kvm_age_page] unexpected type 1

with the patch, and no errors without it.

I have to revert this patch and push a new version out.

-- Steve