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PromQL: Fix panic in parser (#6650)

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Fixes #6649.

The crash is fixed here, was caused because some  AST sanity checks were performed on the syntax tree while assembling it. In case of previous parsing errors this could lead to undefined behaviour.

The fix is to move the checks to the typechecking phase, which runs only when a syntax tree was assembled without there being parsing errors.

There are other places, where similiar checks are performed while assembling the syntax tree. It might be a good idea to move those to the typechecking phase, too. Should I do this in the same or a separate PR?

Signed-off-by: Tobias Guggenmos <tguggenm@redhat.com>
This commit is contained in:
Tobias Guggenmos 2020-01-17 14:06:27 +01:00 committed by Brian Brazil
parent 7d627da97f
commit f5eed7ae0a
2 changed files with 35 additions and 31 deletions
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62
promql/parse.go
View file

@ -350,37 +350,6 @@ func (p *parser) newBinaryExpression(lhs Node, op Item, modifiers Node, rhs Node
ret.RHS = rhs.(Expr)
ret.Op = op.Typ
// opRange returns the PositionRange of the operator part of the BinaryExpr.
// This is made a function instead of a variable, so it is lazily evaluated on demand.
opRange := func() (r PositionRange) {
// Remove whitespace at the beginning and end of the range.
for r.Start = lhs.PositionRange().End; isSpace(rune(p.lex.input[r.Start])); r.Start++ {
}
for r.End = rhs.PositionRange().Start - 1; isSpace(rune(p.lex.input[r.End])); r.End-- {
}
return
}
if ret.ReturnBool && !op.Typ.isComparisonOperator() {
p.failf(opRange(), "bool modifier can only be used on comparison operators")
}
if op.Typ.isComparisonOperator() && !ret.ReturnBool && ret.RHS.Type() == ValueTypeScalar && ret.LHS.Type() == ValueTypeScalar {
p.failf(opRange(), "comparisons between scalars must use BOOL modifier")
}
if op.Typ.isSetOperator() && ret.VectorMatching.Card == CardOneToOne {
ret.VectorMatching.Card = CardManyToMany
}
for _, l1 := range ret.VectorMatching.MatchingLabels {
for _, l2 := range ret.VectorMatching.Include {
if l1 == l2 && ret.VectorMatching.On {
p.failf(opRange(), "label %q must not occur in ON and GROUP clause at once", l1)
}
}
}
return ret
}
@ -524,6 +493,37 @@ func (p *parser) checkType(node Node) (typ ValueType) {
lt := p.checkType(n.LHS)
rt := p.checkType(n.RHS)
// opRange returns the PositionRange of the operator part of the BinaryExpr.
// This is made a function instead of a variable, so it is lazily evaluated on demand.
opRange := func() (r PositionRange) {
// Remove whitespace at the beginning and end of the range.
for r.Start = n.LHS.PositionRange().End; isSpace(rune(p.lex.input[r.Start])); r.Start++ {
}
for r.End = n.RHS.PositionRange().Start - 1; isSpace(rune(p.lex.input[r.End])); r.End-- {
}
return
}
if n.ReturnBool && !n.Op.isComparisonOperator() {
p.failf(opRange(), "bool modifier can only be used on comparison operators")
}
if n.Op.isComparisonOperator() && !n.ReturnBool && n.RHS.Type() == ValueTypeScalar && n.LHS.Type() == ValueTypeScalar {
p.failf(opRange(), "comparisons between scalars must use BOOL modifier")
}
if n.Op.isSetOperator() && n.VectorMatching.Card == CardOneToOne {
n.VectorMatching.Card = CardManyToMany
}
for _, l1 := range n.VectorMatching.MatchingLabels {
for _, l2 := range n.VectorMatching.Include {
if l1 == l2 && n.VectorMatching.On {
p.failf(opRange(), "label %q must not occur in ON and GROUP clause at once", l1)
}
}
}
if !n.Op.isOperator() {
p.failf(n.PositionRange(), "binary expression does not support operator %q", n.Op)
}

4
promql/parse_test.go
View file

@ -2121,6 +2121,10 @@ var testExpr = []struct {
input: "e-+=/(0)",
fail: true,
errMsg: `unexpected "="`,
}, {
input: "a>b()",
fail: true,
errMsg: `unknown function`,
},
// String quoting and escape sequence interpretation tests.
{