Fix PAC buffer overflow (#1883584)

libproxy-0.4.15-fix-CVE-2020-25219.patch

@@ -0,0 +1,57 @@
+From a83dae404feac517695c23ff43ce1e116e2bfbe0 Mon Sep 17 00:00:00 2001
+From: Michael Catanzaro <mcatanzaro@gnome.org>
+Date: Wed, 9 Sep 2020 11:12:02 -0500
+Subject: [PATCH] Rewrite url::recvline to be nonrecursive
+
+This function processes network input. It's semi-trusted, because the
+PAC ought to be trusted. But we still shouldn't allow it to control how
+far we recurse. A malicious PAC can cause us to overflow the stack by
+sending a sufficiently-long line without any '\n' character.
+
+Also, this function failed to properly handle EINTR, so let's fix that
+too, for good measure.
+
+Fixes #134
+---
+ libproxy/url.cpp | 28 ++++++++++++++++++----------
+ 1 file changed, 18 insertions(+), 10 deletions(-)
+
+diff --git a/libproxy/url.cpp b/libproxy/url.cpp
+index ee776b2..68d69cd 100644
+--- a/libproxy/url.cpp
++++ b/libproxy/url.cpp
+@@ -388,16 +388,24 @@ string url::to_string() const {
+ 	return m_orig;
+ }
+ 
+-static inline string recvline(int fd) {
+-	// Read a character.
+-	// If we don't get a character, return empty string.
+-	// If we are at the end of the line, return empty string.
+-	char c = '\0';
+-	
+-	if (recv(fd, &c, 1, 0) != 1 || c == '\n')
+-		return "";
+-
+-	return string(1, c) + recvline(fd);
++static string recvline(int fd) {
++	string line;
++	int ret;
++
++	// Reserve arbitrary amount of space to avoid small memory reallocations.
++	line.reserve(128);
++
++	do {
++		char c;
++		ret = recv(fd, &c, 1, 0);
++		if (ret == 1) {
++			if (c == '\n')
++				return line;
++			line += c;
++		}
++	} while (ret == 1 || (ret == -1 && errno == EINTR));
++
++	return line;
+ }
+ 
+ char* url::get_pac() {

libproxy-0.4.15-fix-pac-buffer-overflow.patch

@@ -0,0 +1,93 @@
+From 4411b523545b22022b4be7d0cac25aa170ae1d3e Mon Sep 17 00:00:00 2001
+From: Fei Li <lifeibiren@gmail.com>
+Date: Fri, 17 Jul 2020 02:18:37 +0800
+Subject: [PATCH] Fix buffer overflow when PAC is enabled
+
+The bug was found on Windows 10 (MINGW64) when PAC is enabled. It turned
+out to be the large PAC file (more than 102400 bytes) returned by a
+local proxy program with no content-length present.
+---
+ libproxy/url.cpp | 44 +++++++++++++++++++++++++++++++-------------
+ 1 file changed, 31 insertions(+), 13 deletions(-)
+
+diff --git a/libproxy/url.cpp b/libproxy/url.cpp
+index ee776b2..8684086 100644
+--- a/libproxy/url.cpp
++++ b/libproxy/url.cpp
+@@ -54,7 +54,7 @@ using namespace std;
+ #define PAC_MIME_TYPE_FB "text/plain"
+ 
+ // This is the maximum pac size (to avoid memory attacks)
+-#define PAC_MAX_SIZE 102400
++#define PAC_MAX_SIZE 0x800000
+ // This is the default block size to use when receiving via HTTP
+ #define PAC_HTTP_BLOCK_SIZE 512
+ 
+@@ -478,15 +478,13 @@ char* url::get_pac() {
+ 		}
+ 
+ 		// Get content
+-		unsigned int recvd = 0;
+-		buffer = new char[PAC_MAX_SIZE];
+-		memset(buffer, 0, PAC_MAX_SIZE);
++		std::vector<char> dynamic_buffer;
+ 		do {
+ 			unsigned int chunk_length;
+ 
+ 			if (chunked) {
+ 				// Discard the empty line if we received a previous chunk
+-				if (recvd > 0) recvline(sock);
++				if (!dynamic_buffer.empty()) recvline(sock);
+ 
+ 				// Get the chunk-length line as an integer
+ 				if (sscanf(recvline(sock).c_str(), "%x", &chunk_length) != 1 || chunk_length == 0) break;
+@@ -498,21 +496,41 @@ char* url::get_pac() {
+ 
+ 			if (content_length >= PAC_MAX_SIZE) break;
+ 
+-			while (content_length == 0 || recvd != content_length) {
+-				int r = recv(sock, buffer + recvd,
+-				             content_length == 0 ? PAC_HTTP_BLOCK_SIZE
+-				                                 : content_length - recvd, 0);
++			while (content_length == 0 || dynamic_buffer.size() != content_length) {
++				// Calculate length to recv
++				unsigned int length_to_read = PAC_HTTP_BLOCK_SIZE;
++				if (content_length > 0)
++					length_to_read = content_length - dynamic_buffer.size();
++
++				// Prepare buffer
++				dynamic_buffer.resize(dynamic_buffer.size() + length_to_read);
++
++				int r = recv(sock, dynamic_buffer.data() + dynamic_buffer.size() - length_to_read, length_to_read, 0);
++
++				// Shrink buffer to fit
++				if (r >= 0)
++					dynamic_buffer.resize(dynamic_buffer.size() - length_to_read + r);
++
++				// PAC size too large, discard
++				if (dynamic_buffer.size() >= PAC_MAX_SIZE) {
++					chunked = false;
++					dynamic_buffer.clear();
++					break;
++				}
++
+ 				if (r <= 0) {
+ 					chunked = false;
+ 					break;
+ 				}
+-				recvd += r;
+ 			}
+ 		} while (chunked);
+ 
+-		if (content_length != 0 && string(buffer).size() != content_length) {
+-			delete[] buffer;
+-			buffer = NULL;
++		if (content_length == 0 || content_length == dynamic_buffer.size()) {
++			buffer = new char[dynamic_buffer.size() + 1];
++			if (!dynamic_buffer.empty()) {
++				memcpy(buffer, dynamic_buffer.data(), dynamic_buffer.size());
++			}
++			buffer[dynamic_buffer.size()] = '\0';
+ 		}
+ 	}
+ 

libproxy.spec

@@ -4,7 +4,7 @@
 
 Name:           libproxy
 Version:        0.4.15
-Release:        23%{?dist}
+Release:        25%{?dist}
 Summary:        A library handling all the details of proxy configuration
 
 License:        LGPLv2+
@@ -27,6 +27,10 @@ Patch5:         libproxy-0.4.15-python39.patch
 Patch6:         libproxy-0.4.15-mozjs68.patch
 # https://github.com/libproxy/libproxy/pull/118
 Patch7:         libproxy-0.4.15-mozjs-use-after-free.patch
+# https://bugzilla.redhat.com/show_bug.cgi?id=1880350
+Patch8:         libproxy-0.4.15-fix-CVE-2020-25219.patch
+# https://bugzilla.redhat.com/show_bug.cgi?id=1883584
+Patch9:         libproxy-0.4.15-fix-pac-buffer-overflow.patch
 
 BuildRequires:  cmake >= 2.6.0
 BuildRequires:  gcc-c++
@@ -230,6 +234,12 @@ install -Dpm 0644 %{SOURCE1} %{buildroot}/%{_mandir}/man1/proxy.1
 
 
 %changelog
+* Tue Sep 29 2020 David King <amigadave@amigadave.com> - 0.4.15-25
+- Fix PAC buffer overflow (#1883584)
+
+* Fri Sep 18 2020 David King <amigadave@amigadave.com> - 0.4.15-24
+- Fix CVE-2020-25219 (#1880350)
+
 * Tue Aug 04 2020 Frantisek Zatloukal <fzatlouk@redhat.com> - 0.4.15-23
 - build with mozjs68
 - backport use after free fix for mozjs backend