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Handle "stack overflow" panic on huge input with regex functions #525

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Handle "stack overflow" panic on huge input with regex functions #525

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19 changes: 13 additions & 6 deletions pm/pm.go
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Original file line number Diff line number Diff line change
Expand Up @@ -5,8 +5,11 @@ import (
"fmt"
)

const EOS = -1
const _UNKNOWN = -2
const (
EOS = -1
_UNKNOWN = -2
maxRecursionLevel = 100000
)

/* Error {{{ */

Expand Down Expand Up @@ -524,7 +527,11 @@ func compilePattern(p pattern, ps ...*iptr) []inst {

// Simple recursive virtual machine based on the
// "Regular Expression Matching: the Virtual Machine Approach" (https://swtch.com/~rsc/regexp/regexp2.html)
func recursiveVM(src []byte, insts []inst, pc, sp int, ms ...*MatchData) (bool, int, *MatchData) {
func recursiveVM(src []byte, insts []inst, pc, sp, recLevel int, ms ...*MatchData) (bool, int, *MatchData) {
recLevel++
if recLevel > maxRecursionLevel {
panic(newError(_UNKNOWN, "pattern/input too complex"))
}
var m *MatchData
if len(ms) == 0 {
m = newMatchState()
Expand All @@ -549,14 +556,14 @@ redo:
pc = inst.Operand1
goto redo
case opSplit:
if ok, nsp, _ := recursiveVM(src, insts, inst.Operand1, sp, m); ok {
if ok, nsp, _ := recursiveVM(src, insts, inst.Operand1, sp, recLevel, m); ok {
return true, nsp, m
}
pc = inst.Operand2
goto redo
case opSave:
s := m.setCapture(inst.Operand1, sp)
if ok, nsp, _ := recursiveVM(src, insts, pc+1, sp, m); ok {
if ok, nsp, _ := recursiveVM(src, insts, pc+1, sp, recLevel, m); ok {
return true, nsp, m
}
m.restoreCapture(inst.Operand1, s)
Expand Down Expand Up @@ -620,7 +627,7 @@ func Find(p string, src []byte, offset, limit int) (matches []*MatchData, err er
insts := compilePattern(pat)
matches = []*MatchData{}
for sp := offset; sp <= len(src); {
ok, nsp, ms := recursiveVM(src, insts, 0, sp)
ok, nsp, ms := recursiveVM(src, insts, 0, sp, 0)
sp++
if ok {
if sp < nsp {
Expand Down