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[BUG]: slice bounds out of range on glob/match #56

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secsys-go opened this issue Jul 12, 2022 · 0 comments
Open

[BUG]: slice bounds out of range on glob/match #56

secsys-go opened this issue Jul 12, 2022 · 0 comments

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@secsys-go
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This bug occurs when the glob.Glob has a matcher which is empty and its length is 0.
In detail, the crash locates in glob/match/raw.go:(self Row) matchAll(s string) bool:

func (self Row) matchAll(s string) bool {
	var idx int
	for _, m := range self.Matchers {
		length := m.Len()

		var next, i int
		for next = range s[idx:] {
			i++
			if i == length {
				break
			}
		}

		if i < length || !m.Match(s[idx:idx+next+1]) {
			return false
		}

		idx += next + 1
	}

	return true
}

If length is 0 and s meets the end, the function won't return by the condition i < length and it will crashed at s[idx:idx+next+1]

The PoC is here:

package main

import (
	"strings"

	"github.com/gobwas/glob"
)
// IndexerGlobFromString parses a comma separated list of patterns and returns a glob.Glob slice suited for repo indexing
func IndexerGlobFromString(globstr string) []glob.Glob {
	extarr := make([]glob.Glob, 0, 10)
	for _, expr := range strings.Split(strings.ToLower(globstr), ",") {
		expr = strings.TrimSpace(expr)
		if expr != "" {
			if g, err := glob.Compile(expr, '.', '/'); err == nil {
				extarr = append(extarr, g)
			}
		}
	}
	return extarr
}

func main() {
	pocstr := "0{" // this string is designed to make the second matcher of g is empty
	g := IndexerGlobFromString(pocstr)[0]
	// the second matcher of g is empty, and its length is 0
	g.Match("0")
}

It will crash as:

panic: runtime error: slice bounds out of range [:2] with length 1

goroutine 1 [running]:
github.com/gobwas/glob/match.Row.matchAll({{0xc0001b6020, 0x2, 0x2}, 0x1, {0xc0001b0090, 0x1, 0x1}}, {0x4d2ca9, 0x1})
	/home/zjx/workspace/gowork/pkg/mod/github.com/gobwas/[email protected]/match/row.go:34 +0x34f
github.com/gobwas/glob/match.Row.Match({{0xc0001b6020, 0x2, 0x2}, 0x1, {0xc0001b0090, 0x1, 0x1}}, {0x4d2ca9, 0x1})
	/home/zjx/workspace/gowork/pkg/mod/github.com/gobwas/[email protected]/match/row.go:56 +0xe9
main.main()
	/home/zjx/workspace/gowork/src/go-fdg-exmaples/gitea/modules/setting/pocTest_newIndexerGlobSettings/main.go:27 +0x7c

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