From de58973a6025f799ee7897a2cf58bb01eca87631 Mon Sep 17 00:00:00 2001
From: Eric Wong <normalperson@yhbt.net>
Date: Mon, 19 Apr 2010 13:40:37 -0700
Subject: [PATCH] http: negative/invalid Content-Length raises exception

...instead of tripping an assertion.

This fixes a potential denial-of-service for servers exposed directly
to untrusted clients.

This bug does not affect supported Unicorn deployments as Unicorn is
only supported with trusted clients (such as nginx) on a LAN.  nginx is
known to reject clients that send invalid Content-Length headers, so any
deployments on a trusted LAN and/or behind nginx are safe.

Servers affected by this bug include (but are not limited to) Rainbows!
and Zbatery.  This does not affect Thin nor Mongrel which never got
request body filtering treatment that the Unicorn HTTP parser got in
August 2009.
---
 ext/unicorn_http/c_util.h        |  8 ++++++--
 test/unit/test_http_parser_ng.rb | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/ext/unicorn_http/c_util.h b/ext/unicorn_http/c_util.h
index 8542b3d3..ab1fc0e3 100644
--- a/ext/unicorn_http/c_util.h
+++ b/ext/unicorn_http/c_util.h
@@ -108,8 +108,12 @@ static off_t parse_length(const char *value, size_t length)
 {
   off_t rv;
 
-  for (rv = 0; length-- && rv >= 0; ++value)
-    rv = step_incr(rv, *value, 10);
+  for (rv = 0; length-- && rv >= 0; ++value) {
+    if (*value >= '0' && *value <= '9')
+      rv = step_incr(rv, *value, 10);
+    else
+      return -1;
+  }
 
   return rv;
 }
diff --git a/test/unit/test_http_parser_ng.rb b/test/unit/test_http_parser_ng.rb
index 49802493..3b9111f5 100644
--- a/test/unit/test_http_parser_ng.rb
+++ b/test/unit/test_http_parser_ng.rb
@@ -416,4 +416,24 @@ class HttpParserNgTest < Test::Unit::TestCase
     end
   end
 
+  def test_negative_content_length
+    req = {}
+    str = "PUT / HTTP/1.1\r\n" \
+          "Content-Length: -1\r\n" \
+          "\r\n"
+    assert_raises(HttpParserError) do
+      @parser.headers(req, str)
+    end
+  end
+
+  def test_invalid_content_length
+    req = {}
+    str = "PUT / HTTP/1.1\r\n" \
+          "Content-Length: zzzzz\r\n" \
+          "\r\n"
+    assert_raises(HttpParserError) do
+      @parser.headers(req, str)
+    end
+  end
+
 end
-- 
2.11.4.GIT