zip_archive: reject files that don't start with an LFH signature.

Bug: 64211847
Test: zip_archive_test

(cherry picked from commit c1a56dcab711a7ee238c0af865920ca51b1408a6)

Merged-In: I275e7c4da05ceeb20401b560c72294f29ef63642
Change-Id: Ib89f0def696206ff427be27764c158fab88e4b5d
CVE-2017-13156

2 files changed, 67 insertions, 0 deletions

diff --git a/libziparchive/zip_archive.cc b/libziparchive/zip_archive.cc
index 8c2c559b1..b93d192fe 100644
--- a/libziparchive/zip_archive.cc
+++ b/libziparchive/zip_archive.cc
@@ -552,6 +552,8 @@ static int32_t MapCentralDirectory(int fd, const char* debug_file_name,
   return result;
 }
 
+static inline ssize_t ReadAtOffset(int fd, uint8_t* buf, size_t len, off64_t off);
+
 /*
  * Parses the Zip archive's Central Directory.  Allocates and populates the
  * hash table.
@@ -630,6 +632,22 @@ static int32_t ParseZipArchive(ZipArchive* archive) {
       return -1;
     }
   }
+
+  uint32_t lfh_start_bytes;
+  if (!ReadAtOffset(archive->fd, reinterpret_cast<uint8_t*>(&lfh_start_bytes),
+                    sizeof(uint32_t), 0)) {
+    ALOGW("Zip: Unable to read header for entry at offset == 0.");
+    return -1;
+  }
+
+  if (lfh_start_bytes != LocalFileHeader::kSignature) {
+    ALOGW("Zip: Entry at offset zero has invalid LFH signature %" PRIx32, lfh_start_bytes);
+#if defined(__ANDROID__)
+    android_errorWriteLog(0x534e4554, "64211847");
+#endif
+    return -1;
+  }
+
   ALOGV("+++ zip good scan %" PRIu16 " entries", num_entries);
 
   return 0;
diff --git a/libziparchive/zip_archive_test.cc b/libziparchive/zip_archive_test.cc
index c79986957..89eb496cc 100644
--- a/libziparchive/zip_archive_test.cc
+++ b/libziparchive/zip_archive_test.cc
@@ -530,6 +530,55 @@ TEST(ziparchive, ExtractToFile) {
   close(fd);
 }
 
+// A zip file whose local file header at offset zero is corrupted.
+//
+// ---------------
+// cat foo > a.txt
+// zip a.zip a.txt
+// cat a.zip | xxd -i
+//
+// Manual changes :
+// [2] = 0xff  // Corrupt the LFH signature of entry 0.
+// [3] = 0xff  // Corrupt the LFH signature of entry 0.
+static const std::vector<uint8_t> kZipFileWithBrokenLfhSignature{
+    //[lfh-sig-----------], [lfh contents---------------------------------
+    0x50, 0x4b, 0xff, 0xff, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x77, 0x80,
+    //--------------------------------------------------------------------
+    0x09, 0x4b, 0xa8, 0x65, 0x32, 0x7e, 0x04, 0x00, 0x00, 0x00, 0x04, 0x00,
+    //-------------------------------]  [file-name-----------------], [---
+    0x00, 0x00, 0x05, 0x00, 0x1c, 0x00, 0x61, 0x2e, 0x74, 0x78, 0x74, 0x55,
+    // entry-contents------------------------------------------------------
+    0x54, 0x09, 0x00, 0x03, 0x51, 0x24, 0x8b, 0x59, 0x51, 0x24, 0x8b, 0x59,
+    //--------------------------------------------------------------------
+    0x75, 0x78, 0x0b, 0x00, 0x01, 0x04, 0x89, 0x42, 0x00, 0x00, 0x04, 0x88,
+    //-------------------------------------], [cd-record-sig-------], [---
+    0x13, 0x00, 0x00, 0x66, 0x6f, 0x6f, 0x0a, 0x50, 0x4b, 0x01, 0x02, 0x1e,
+    // cd-record-----------------------------------------------------------
+    0x03, 0x0a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x77, 0x80, 0x09, 0x4b, 0xa8,
+    //--------------------------------------------------------------------
+    0x65, 0x32, 0x7e, 0x04, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x05,
+    //--------------------------------------------------------------------
+    0x00, 0x18, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xa0,
+    //-]  [lfh-file-header-off-], [file-name-----------------], [extra----
+    0x81, 0x00, 0x00, 0x00, 0x00, 0x61, 0x2e, 0x74, 0x78, 0x74, 0x55, 0x54,
+    //--------------------------------------------------------------------
+    0x05, 0x00, 0x03, 0x51, 0x24, 0x8b, 0x59, 0x75, 0x78, 0x0b, 0x00, 0x01,
+    //-------------------------------------------------------], [eocd-sig-
+    0x04, 0x89, 0x42, 0x00, 0x00, 0x04, 0x88, 0x13, 0x00, 0x00, 0x50, 0x4b,
+    //-------], [---------------------------------------------------------
+    0x05, 0x06, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x01, 0x00, 0x4b, 0x00,
+    //-------------------------------------------]
+    0x00, 0x00, 0x43, 0x00, 0x00, 0x00, 0x00, 0x00};
+
+TEST(ziparchive, BrokenLfhSignature) {
+  TemporaryFile tmp_file;
+  ASSERT_NE(-1, tmp_file.fd);
+  ASSERT_TRUE(android::base::WriteFully(tmp_file.fd, &kZipFileWithBrokenLfhSignature[0],
+                                        kZipFileWithBrokenLfhSignature.size()));
+  ZipArchiveHandle handle;
+  ASSERT_EQ(-1, OpenArchiveFd(tmp_file.fd, "LeadingNonZipBytes", &handle));
+}
+
 int main(int argc, char** argv) {
   ::testing::InitGoogleTest(&argc, argv);