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PrepareForEval panics on empty input #2054

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omri86 opened this issue Feb 3, 2020 · 1 comment · Fixed by #2060
Closed

PrepareForEval panics on empty input #2054

omri86 opened this issue Feb 3, 2020 · 1 comment · Fixed by #2060
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@patrick-east
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@omri86
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omri86 commented Feb 3, 2020

Expected Behavior

Running the following code in order to pre-compile the rego policy should return an error (in my opinion):

	res, err := rego.New(
		rego.Query("d"),
		rego.Module("example.rego", ""),
	).PrepareForEval(context.Background())

This happens when the input is empty or contains only comments
e.g., this input will also fail:

input := `# comment
# another comment`

Actual Behavior

Ran it as a test, and got a panic: runtime error: invalid memory address or nil pointer dereference

=== RUN   TestRego
--- FAIL: TestRego (0.00s)
panic: runtime error: invalid memory address or nil pointer dereference [recovered]
	panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0xb83327]

goroutine 39 [running]:
testing.tRunner.func1(0xc00014c200)
	/usr/local/go/src/testing/testing.go:874 +0x3a3
panic(0x1df4360, 0x3cc5d50)
	/usr/local/go/src/runtime/panic.go:679 +0x1b2
/vendor/github.com/open-policy-agent/opa/ast.(*Module).Copy(0x0, 0xc0005f7438)
	/.../vendor/github.com/open-policy-agent/opa/ast/policy.go:227 +0x47
/vendor/github.com/open-policy-agent/opa/ast.(*Compiler).Compile(0xc0001b65b0, 0xc0005f7438)
	/.../vendor/github.com/open-policy-agent/opa/ast/compile.go:339 +0x107
/vendor/github.com/open-policy-agent/opa/bundle.writeModules(0x2a69f00, 0xc00005a178, 0x2a9ae40, 0xc0002f2000, 0x2a0f840, 0xc00043bf80, 0xc0001b65b0, 0x2a85060, 0xc0001d1fc0, 0xc00043bf20, ...)
	/.../vendor/github.com/open-policy-agent/opa/bundle/store.go:397 +0x598
/vendor/github.com/open-policy-agent/opa/bundle.activateBundles(0xc0005f7ac0, 0xc00005a178, 0x2a9ae40)
	/.../vendor/github.com/open-policy-agent/opa/bundle/store.go:243 +0x817
/vendor/github.com/open-policy-agent/opa/bundle.Activate(...)
	/.../vendor/github.com/open-policy-agent/opa/bundle/store.go:161
/vendor/github.com/open-policy-agent/opa/rego.(*Rego).compileModules(0xc000116000, 0x2a69f00, 0xc00005a178, 0x2a0f840, 0xc00043bf80, 0x2a85060, 0xc0001d1fc0, 0x0, 0x0)
	/.../vendor/github.com/open-policy-agent/opa/rego/rego.go:1430 +0x1b5
/vendor/github.com/open-policy-agent/opa/rego.(*Rego).prepare(0xc000116000, 0x2a69f00, 0xc00005a178, 0x0, 0xc0005f7c80, 0x1, 0x1, 0x0, 0x1842eea3b5116228)
	/.../vendor/github.com/open-policy-agent/opa/rego/rego.go:1259 +0x1f4
/vendor/github.com/open-policy-agent/opa/rego.(*Rego).PrepareForEval(0xc000116000, 0x2a69f00, 0xc00005a178, 0x0, 0x0, 0x0, 0x0, 0x1, 0xc00044c020, 0x453d28)
	/...vendor/github.com/open-policy-agent/opa/rego/rego.go:1174 +0x4aa
/.../TestRego(0xc00014c200)
	/.../some_test.go... +0xf7
testing.tRunner(0xc00014c200, 0x21ffbf8)
	/usr/local/go/src/testing/testing.go:909 +0xc9
created by testing.(*T).Run
	/usr/local/go/src/testing/testing.go:960 +0x350

Process finished with exit code 1

Steps to Reproduce the Problem

  1. Integrating with OPA Go API @ version v0.15.1
  2. Create and run the following test:
	res, err := rego.New(
		rego.Query("d"),
		rego.Module("example.rego", ""),
	).PrepareForEval(context.Background())

Additional Info

  • Did not find any duplicate issue
  • I know that the query doesn't really make sense, but still - in my opinion - this shouldn't panic
@omri86 omri86 changed the title PrepareForEval panics on empty script PrepareForEval panics on empty input Feb 3, 2020
@tsandall tsandall added the bug label Feb 3, 2020
@tsandall
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tsandall commented Feb 3, 2020

You're correct that OPA should not panic. In this case, I'd expect an error since the parser should reject an empty module/file.

@patrick-east patrick-east self-assigned this Feb 5, 2020
@patrick-east patrick-east mentioned this issue Feb 5, 2020
Merged
patrick-east added a commit to patrick-east/opa that referenced this issue Feb 21, 2020
@patrick-east
ast: Return an error when parsing an empty module
10f0627 
The documentation is pretty clear that a module must at least contain
a package, so it is safe to say that an empty file isn't valid.

Previously the helper would just return a nil module and nil error, it
will now return an error.

Fixes: open-policy-agent#2054
Signed-off-by: Patrick East <east.patrick@gmail.com>
patrick-east added a commit that referenced this issue Feb 21, 2020
@patrick-east
ast: Return an error when parsing an empty module
55b474a 
The documentation is pretty clear that a module must at least contain
a package, so it is safe to say that an empty file isn't valid.

Previously the helper would just return a nil module and nil error, it
will now return an error.

Fixes: #2054
Signed-off-by: Patrick East <east.patrick@gmail.com>
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ast: Return an error when parsing an empty module patrick-east/opa
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@tsandall @patrick-east @omri86