Fix git-daemon hang on invalid input (CVE-2009-2108, bug 505761)

git-1.6.3.2-daemon-extra-args.patch

@@ -0,0 +1,104 @@
+From 73bb33a94ec67a53e7d805b12ad9264fa25f4f8d Mon Sep 17 00:00:00 2001
+From: Shawn O. Pearce <spearce@spearce.org>
+Date: Thu, 4 Jun 2009 18:33:32 -0700
+Subject: [PATCH] daemon: Strictly parse the "extra arg" part of the command
+
+Since 1.4.4.5 (49ba83fb67 "Add virtualization support to git-daemon")
+git daemon enters an infinite loop and never terminates if a client
+hides any extra arguments in the initial request line which is not
+exactly "\0host=blah\0".
+
+Since that change, a client must never insert additional extra
+arguments, or attempt to use any argument other than "host=", as
+any daemon will get stuck parsing the request line and will never
+complete the request.
+
+Since the client can't tell if the daemon is patched or not, it
+is not possible to know if additional extra args might actually be
+able to be safely requested.
+
+If we ever need to extend the git daemon protocol to support a new
+feature, we may have to do something like this to the exchange:
+
+  # If both support git:// v2
+  #
+  C: 000cgit://v2
+  S: 0010ok host user
+  C: 0018host git.kernel.org
+  C: 0027git-upload-pack /pub/linux-2.6.git
+  S: ...git-upload-pack header...
+
+  # If client supports git:// v2, server does not:
+  #
+  C: 000cgit://v2
+  S: <EOF>
+
+  C: 003bgit-upload-pack /pub/linux-2.6.git\0host=git.kernel.org\0
+  S: ...git-upload-pack header...
+
+This requires the client to create two TCP connections to talk to
+an older git daemon, however all daemons since the introduction of
+daemon.c will safely reject the unknown "git://v2" command request,
+so the client can quite easily determine the server supports an
+older protocol.
+
+Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
+Signed-off-by: Junio C Hamano <gitster@pobox.com>
+
+diff --git a/connect.c b/connect.c
+index f6b8ba6..958c831 100644
+--- a/connect.c
++++ b/connect.c
+@@ -579,7 +579,10 @@ struct child_process *git_connect(int fd[2], const char *url_orig,
+ 			git_tcp_connect(fd, host, flags);
+ 		/*
+ 		 * Separate original protocol components prog and path
+-		 * from extended components with a NUL byte.
++		 * from extended host header with a NUL byte.
++		 *
++		 * Note: Do not add any other headers here!  Doing so
++		 * will cause older git-daemon servers to crash.
+ 		 */
+ 		packet_write(fd[1],
+ 			     "%s %s%chost=%s%c",
+diff --git a/daemon.c b/daemon.c
+index daa4c8e..b2babcc 100644
+--- a/daemon.c
++++ b/daemon.c
+@@ -406,15 +406,15 @@ static char *xstrdup_tolower(const char *str)
+ }
+ 
+ /*
+- * Separate the "extra args" information as supplied by the client connection.
++ * Read the host as supplied by the client connection.
+  */
+-static void parse_extra_args(char *extra_args, int buflen)
++static void parse_host_arg(char *extra_args, int buflen)
+ {
+ 	char *val;
+ 	int vallen;
+ 	char *end = extra_args + buflen;
+ 
+-	while (extra_args < end && *extra_args) {
++	if (extra_args < end && *extra_args) {
+ 		saw_extended_args = 1;
+ 		if (strncasecmp("host=", extra_args, 5) == 0) {
+ 			val = extra_args + 5;
+@@ -436,6 +436,8 @@ static void parse_extra_args(char *extra_args, int buflen)
+ 			/* On to the next one */
+ 			extra_args = val + vallen;
+ 		}
++		if (extra_args < end && *extra_args)
++			die("Invalid request");
+ 	}
+ 
+ 	/*
+@@ -545,7 +547,7 @@ static int execute(struct sockaddr *addr)
+ 	hostname = canon_hostname = ip_address = tcp_port = NULL;
+ 
+ 	if (len != pktlen)
+-		parse_extra_args(line + len + 1, pktlen - len - 1);
++		parse_host_arg(line + len + 1, pktlen - len - 1);
+ 
+ 	for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
+ 		struct daemon_service *s = &(daemon_service[i]);

git.spec

@@ -1,7 +1,7 @@
 # Pass --without docs to rpmbuild if you don't want the documentation
 Name:           git
 Version:        1.6.3.2
-Release:        1%{?dist}
+Release:        2%{?dist}
 Summary:        Core git tools
 License:        GPLv2
 Group:          Development/Tools
@@ -14,6 +14,8 @@ Source4:        git-gui.desktop
 Patch0:         git-1.5-gitweb-home-link.patch
 # https://bugzilla.redhat.com/490602
 Patch1:         git-cvsimport-Ignore-cvsps-2.2b1-Branches-output.patch
+# http://git.kernel.org/?p=git/git.git;a=commitdiff;h=73bb33a9
+Patch2:         git-1.6.3.2-daemon-extra-args.patch
 BuildRoot:      %{_tmppath}/%{name}-%{version}-%{release}-root-%(%{__id_u} -n)
 
 BuildRequires:  desktop-file-utils
@@ -187,6 +189,7 @@ Requires:       git = %{version}-%{release}, emacs-common >= 22.2
 %setup -q
 %patch0 -p1
 %patch1 -p1
+%patch2 -p1
 
 # Use these same options for every invocation of 'make'.
 # Otherwise it will rebuild in %%install due to flags changes.
@@ -363,6 +366,9 @@ rm -rf $RPM_BUILD_ROOT
 # No files for you!
 
 %changelog
+* Fri Jun 19 2009 Todd Zullinger <tmz@pobox.com> - 1.6.3.2-2
+- Fix git-daemon hang on invalid input (CVE-2009-2108, bug 505761)
+
 * Fri Jun 05 2009 Todd Zullinger <tmz@pobox.com> - 1.6.3.2-1
 - git-1.6.3.2
 - Require emacs >= 22.2 for emacs support (bug 495312)