From 172229966c9c69305d7b6b9b69552346343fe270 Mon Sep 17 00:00:00 2001 From: zeripath Date: Wed, 20 Jan 2021 15:10:50 +0000 Subject: [PATCH] Prevent panic on fuzzer provided string (#14405) * Prevent panic on fuzzer provided string The fuzzer has found that providing a tag with an attribute to PostProcess causes a panic. This PR removes any rendered html or body tags from the output. Signed-off-by: Andrew Thornton * Placate lint * placate lint again Signed-off-by: Andrew Thornton * minor cleanup Signed-off-by: Andrew Thornton --- modules/markup/html.go | 38 +++++++++++++++++++++++++++---------- modules/markup/html_test.go | 25 ++++++++++++++++++++++++ 2 files changed, 53 insertions(+), 10 deletions(-) diff --git a/modules/markup/html.go b/modules/markup/html.go index 9e4b1a3d5d..67aec7371c 100644 --- a/modules/markup/html.go +++ b/modules/markup/html.go @@ -317,9 +317,6 @@ func RenderEmoji( return ctx.postProcess(rawHTML) } -var byteBodyTag = []byte("") -var byteBodyTagClosing = []byte("") - func (ctx *postProcessCtx) postProcess(rawHTML []byte) ([]byte, error) { if ctx.procs == nil { ctx.procs = defaultProcessors @@ -327,9 +324,9 @@ func (ctx *postProcessCtx) postProcess(rawHTML []byte) ([]byte, error) { // give a generous extra 50 bytes res := make([]byte, 0, len(rawHTML)+50) - res = append(res, byteBodyTag...) + res = append(res, ""...) res = append(res, rawHTML...) - res = append(res, byteBodyTagClosing...) + res = append(res, ""...) // parse the HTML nodes, err := html.ParseFragment(bytes.NewReader(res), nil) @@ -341,6 +338,31 @@ func (ctx *postProcessCtx) postProcess(rawHTML []byte) ([]byte, error) { ctx.visitNode(node, true) } + newNodes := make([]*html.Node, 0, len(nodes)) + + for _, node := range nodes { + if node.Data == "html" { + node = node.FirstChild + for node != nil && node.Data != "body" { + node = node.NextSibling + } + } + if node == nil { + continue + } + if node.Data == "body" { + child := node.FirstChild + for child != nil { + newNodes = append(newNodes, child) + child = child.NextSibling + } + } else { + newNodes = append(newNodes, node) + } + } + + nodes = newNodes + // Create buffer in which the data will be placed again. We know that the // length will be at least that of res; to spare a few alloc+copy, we // reuse res, resetting its length to 0. @@ -353,12 +375,8 @@ func (ctx *postProcessCtx) postProcess(rawHTML []byte) ([]byte, error) { } } - // remove initial parts - because Render creates a whole HTML page. - res = buf.Bytes() - res = res[bytes.Index(res, byteBodyTag)+len(byteBodyTag) : bytes.LastIndex(res, byteBodyTagClosing)] - // Everything done successfully, return parsed data. - return res, nil + return buf.Bytes(), nil } func (ctx *postProcessCtx) visitNode(node *html.Node, visitText bool) { diff --git a/modules/markup/html_test.go b/modules/markup/html_test.go index b04781489a..a78b936f87 100644 --- a/modules/markup/html_test.go +++ b/modules/markup/html_test.go @@ -383,3 +383,28 @@ func TestRender_ShortLinks(t *testing.T) { `

[[foobar]]

`, `

[[foobar]]

`) } + +func Test_ParseClusterFuzz(t *testing.T) { + setting.AppURL = AppURL + setting.AppSubURL = AppSubURL + + var localMetas = map[string]string{ + "user": "go-gitea", + "repo": "gitea", + } + + data := "