From 4292c49b93cd018c300cd8321151afa0cd051387 Mon Sep 17 00:00:00 2001
From: Robert Scott <code@humanleg.org.uk>
Date: Mon, 24 Jan 2022 19:08:38 +0000
Subject: [PATCH] expat: add patches for CVE-2022-23852

---
 .../libraries/expat/CVE-2022-23852-fix.patch  | 26 +++++++++
 .../libraries/expat/CVE-2022-23852-test.patch | 55 +++++++++++++++++++
 pkgs/development/libraries/expat/default.nix  |  6 ++
 3 files changed, 87 insertions(+)
 create mode 100644 pkgs/development/libraries/expat/CVE-2022-23852-fix.patch
 create mode 100644 pkgs/development/libraries/expat/CVE-2022-23852-test.patch

diff --git a/pkgs/development/libraries/expat/CVE-2022-23852-fix.patch b/pkgs/development/libraries/expat/CVE-2022-23852-fix.patch
new file mode 100644
index 000000000000..fbbd080db4ed
--- /dev/null
+++ b/pkgs/development/libraries/expat/CVE-2022-23852-fix.patch
@@ -0,0 +1,26 @@
+From 847a645152f5ebc10ac63b74b604d0c1a79fae40 Mon Sep 17 00:00:00 2001
+From: Samanta Navarro <ferivoz@riseup.net>
+Date: Sat, 22 Jan 2022 17:48:00 +0100
+Subject: [PATCH] lib: Detect and prevent integer overflow in XML_GetBuffer
+ (CVE-2022-23852)
+
+---
+ expat/lib/xmlparse.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/expat/lib/xmlparse.c b/expat/lib/xmlparse.c
+index d54af683..5ce31402 100644
+--- a/expat/lib/xmlparse.c
++++ b/expat/lib/xmlparse.c
+@@ -2067,6 +2067,11 @@ XML_GetBuffer(XML_Parser parser, int len) {
+     keep = (int)EXPAT_SAFE_PTR_DIFF(parser->m_bufferPtr, parser->m_buffer);
+     if (keep > XML_CONTEXT_BYTES)
+       keep = XML_CONTEXT_BYTES;
++    /* Detect and prevent integer overflow */
++    if (keep > INT_MAX - neededSize) {
++      parser->m_errorCode = XML_ERROR_NO_MEMORY;
++      return NULL;
++    }
+     neededSize += keep;
+ #endif /* defined XML_CONTEXT_BYTES */
+     if (neededSize
diff --git a/pkgs/development/libraries/expat/CVE-2022-23852-test.patch b/pkgs/development/libraries/expat/CVE-2022-23852-test.patch
new file mode 100644
index 000000000000..3dca8f914a8f
--- /dev/null
+++ b/pkgs/development/libraries/expat/CVE-2022-23852-test.patch
@@ -0,0 +1,55 @@
+From acf956f14bf79a5e6383a969aaffec98bfbc2e44 Mon Sep 17 00:00:00 2001
+From: Sebastian Pipping <sebastian@pipping.org>
+Date: Sun, 23 Jan 2022 18:17:04 +0100
+Subject: [PATCH] tests: Cover integer overflow in XML_GetBuffer
+ (CVE-2022-23852)
+
+---
+ expat/tests/runtests.c | 27 +++++++++++++++++++++++++++
+ 1 file changed, 27 insertions(+)
+
+diff --git a/expat/tests/runtests.c b/expat/tests/runtests.c
+index e89e8220..579dad1a 100644
+--- a/expat/tests/runtests.c
++++ b/expat/tests/runtests.c
+@@ -3847,6 +3847,30 @@ START_TEST(test_get_buffer_2) {
+ }
+ END_TEST
+ 
++/* Test for signed integer overflow CVE-2022-23852 */
++#if defined(XML_CONTEXT_BYTES)
++START_TEST(test_get_buffer_3_overflow) {
++  XML_Parser parser = XML_ParserCreate(NULL);
++  assert(parser != NULL);
++
++  const char *const text = "\n";
++  const int expectedKeepValue = (int)strlen(text);
++
++  // After this call, variable "keep" in XML_GetBuffer will
++  // have value expectedKeepValue
++  if (XML_Parse(parser, text, (int)strlen(text), XML_FALSE /* isFinal */)
++      == XML_STATUS_ERROR)
++    xml_failure(parser);
++
++  assert(expectedKeepValue > 0);
++  if (XML_GetBuffer(parser, INT_MAX - expectedKeepValue + 1) != NULL)
++    fail("enlarging buffer not failed");
++
++  XML_ParserFree(parser);
++}
++END_TEST
++#endif // defined(XML_CONTEXT_BYTES)
++
+ /* Test position information macros */
+ START_TEST(test_byte_info_at_end) {
+   const char *text = "<doc></doc>";
+@@ -11731,6 +11755,9 @@ make_suite(void) {
+   tcase_add_test(tc_basic, test_empty_parse);
+   tcase_add_test(tc_basic, test_get_buffer_1);
+   tcase_add_test(tc_basic, test_get_buffer_2);
++#if defined(XML_CONTEXT_BYTES)
++  tcase_add_test(tc_basic, test_get_buffer_3_overflow);
++#endif
+   tcase_add_test(tc_basic, test_byte_info_at_end);
+   tcase_add_test(tc_basic, test_byte_info_at_error);
+   tcase_add_test(tc_basic, test_byte_info_at_cdata);
diff --git a/pkgs/development/libraries/expat/default.nix b/pkgs/development/libraries/expat/default.nix
index 6abbd9567478..5bd03824441a 100644
--- a/pkgs/development/libraries/expat/default.nix
+++ b/pkgs/development/libraries/expat/default.nix
@@ -14,6 +14,12 @@ stdenv.mkDerivation rec {
     sha256 = "sha256-sfnxsaXrsKyqiMn/eb+k4UWCO3iqUYXlxdhfBggkd4o=";
   };
 
+  patches = [
+    ./CVE-2022-23852-fix.patch
+    ./CVE-2022-23852-test.patch
+  ];
+  patchFlags = "-p2";
+
   outputs = [ "out" "dev" ]; # TODO: fix referrers
   outputBin = "dev";