From 119fb187192a9ea13dc90d9d20c215fc82799ab9 Mon Sep 17 00:00:00 2001
From: Patrick Monnerat <patrick@monnerat.net>
Date: Mon, 13 Feb 2023 08:33:09 +0100
Subject: [PATCH] content_encoding: do not reset stage counter for each header

Test 418 verifies

Closes #10492

CVE: CVE-2023-23916
Upstream-Status: Backport [https://github.com/curl/curl/commit/119fb187192a9ea13dc.patch]
Signed-off-by: Pawan Badganchi <Pawan.Badganchi@kpit.com>
---
 lib/content_encoding.c  |   7 +-
 lib/urldata.h           |   1 +
 tests/data/Makefile.inc |   2 +-
 tests/data/test387      |   2 +-
 tests/data/test418      | 152 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 158 insertions(+), 6 deletions(-)
 create mode 100644 tests/data/test418

--- a/lib/content_encoding.c
+++ b/lib/content_encoding.c
@@ -1037,7 +1037,6 @@ CURLcode Curl_build_unencoding_stack(str
                                      const char *enclist, int maybechunked)
 {
   struct SingleRequest *k = &data->req;
-  int counter = 0;
 
   do {
     const char *name;
@@ -1072,9 +1071,9 @@ CURLcode Curl_build_unencoding_stack(str
       if(!encoding)
         encoding = &error_encoding;  /* Defer error at stack use. */
 
-      if(++counter >= MAX_ENCODE_STACK) {
-        failf(data, "Reject response due to %u content encodings",
-              counter);
+      if(k->writer_stack_depth++ >= MAX_ENCODE_STACK) {
+        failf(data, "Reject response due to more than %u content encodings",
+              MAX_ENCODE_STACK);
         return CURLE_BAD_CONTENT_ENCODING;
       }
       /* Stack the unencoding stage. */
--- a/lib/urldata.h
+++ b/lib/urldata.h
@@ -682,6 +682,7 @@ struct SingleRequest {
   struct dohdata *doh; /* DoH specific data for this request */
 #endif
   unsigned char setcookies;
+  unsigned char writer_stack_depth; /* Unencoding stack depth. */
   BIT(header);        /* incoming data has HTTP header */
   BIT(content_range); /* set TRUE if Content-Range: was found */
   BIT(upload_done);   /* set to TRUE when doing chunked transfer-encoding
--- a/tests/data/Makefile.inc
+++ b/tests/data/Makefile.inc
@@ -69,6 +69,7 @@
 \
 test400 test401 test402 test403 test404 test405 test406 test407 test408 \
 test409 test410 \
+test418 \
 \
 test430 test431 test432 test433 test434 test435 test436 \
 \
--- /dev/null
+++ b/tests/data/test418
@@ -0,0 +1,152 @@
+<testcase>
+<info>
+<keywords>
+HTTP
+gzip
+</keywords>
+</info>
+
+#
+# Server-side
+<reply>
+<data nocheck="yes">
+HTTP/1.1 200 OK
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+Transfer-Encoding: gzip
+
+-foo-
+</data>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+http
+</server>
+ <name>
+Response with multiple Transfer-Encoding headers
+ </name>
+ <command>
+http://%HOSTIP:%HTTPPORT/%TESTNUMBER -sS
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol crlf="yes">
+GET /%TESTNUMBER HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+
+</protocol>
+
+# CURLE_BAD_CONTENT_ENCODING is 61
+<errorcode>
+61
+</errorcode>
+<stderr mode="text">
+curl: (61) Reject response due to more than 5 content encodings
+</stderr>
+</verify>
+</testcase>
