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net.urllib: fix #9748 out of bounds accesses in unescape() (#9770)

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pancake 2021-04-19 15:43:35 +02:00 committed by GitHub
parent aa3a8c5245
commit 49330af715
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1 changed files with 12 additions and 2 deletions
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14
vlib/net/urllib/urllib.v
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@ -176,7 +176,8 @@ fn unescape(s_ string, mode EncodingMode) ?string {
// But https://tools.ietf.org/html/rfc6874#section-2
// introduces %25 being allowed to escape a percent sign
// in IPv6 scoped-address literals. Yay.
if mode == .encode_host && unhex(s[i + 1]) < 8 && s[i..i + 3] != '%25' {
if i + 3 >= s.len && mode == .encode_host && unhex(s[i + 1]) < 8
&& s[i..i + 3] != '%25' {
return error(error_msg(urllib.err_msg_escape, s[i..i + 3]))
}
if mode == .encode_zone {
@ -187,6 +188,9 @@ fn unescape(s_ string, mode EncodingMode) ?string {
// That is, you can use escaping in the zone identifier but not
// to introduce bytes you couldn't just write directly.
// But Windows puts spaces here! Yay.
if i + 3 >= s.len {
return error(error_msg('unescape: invalid escape sequence', ''))
}
v := ((unhex(s[i + 1]) << byte(4)) | unhex(s[i + 2]))
if s[i..i + 3] != '%25' && v != ` ` && should_escape(v, .encode_host) {
error(error_msg(urllib.err_msg_escape, s[i..i + 3]))
@ -210,11 +214,17 @@ fn unescape(s_ string, mode EncodingMode) ?string {
if n == 0 && !has_plus {
return s
}
if s.len < 2 * n {
return error(error_msg('unescape: invalid escape sequence', ''))
}
mut t := strings.new_builder(s.len - 2 * n)
for i := 0; i < s.len; i++ {
x := s[i]
match x {
`%` {
if i + 2 >= s.len {
return error(error_msg('unescape: invalid escape sequence', ''))
}
t.write_string(((unhex(s[i + 1]) << byte(4)) | unhex(s[i + 2])).ascii_str())
i += 2
}
@ -268,7 +278,7 @@ fn escape(s string, mode EncodingMode) string {
if required <= buf.len {
t = buf[..required]
} else {
t = []byte{len: (required)}
t = []byte{len: required}
}
if hex_count == 0 {
copy(t, s.bytes())