Credit to OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=51751

Credit to OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=52053
Avoid null pointer deref and heap buffer overflow.

src/quicktimevideo.cpp

@@ -575,6 +575,14 @@ void QuickTimeVideo::decodeBlock(std::string const& entered_from) {
   tagDecoder(buf, newsize);
 }  // QuickTimeVideo::decodeBlock
 
+static std::string readString(BasicIo& io, size_t size) {
+  enforce(size <= io.size() - io.tell(), Exiv2::ErrorCode::kerCorruptedMetadata);
+  Exiv2::DataBuf str(size + 1);
+  io.readOrThrow(str.data(), size);
+  str.write_uint8(size, 0); // nul-terminate string
+  return Exiv2::toString(str.data());
+}
+
 void QuickTimeVideo::tagDecoder(Exiv2::DataBuf& buf, size_t size) {
   assert(buf.size() > 4);
 
@@ -626,30 +634,21 @@ void QuickTimeVideo::tagDecoder(Exiv2::DataBuf& buf, size_t size) {
     keysTagDecoder(size);
 
   else if (equalsQTimeTag(buf, "url ")) {
-    Exiv2::DataBuf url(size + 1);
-    io_->readOrThrow(url.data(), size);
-    url.write_uint8(size, 0);
     if (currentStream_ == Video)
-      xmpData_["Xmp.video.URL"] = Exiv2::toString(url.data());
+      xmpData_["Xmp.video.URL"] = readString(*io_, size);
     else if (currentStream_ == Audio)
-      xmpData_["Xmp.audio.URL"] = Exiv2::toString(url.data());
+      xmpData_["Xmp.audio.URL"] = readString(*io_, size);
   }
 
   else if (equalsQTimeTag(buf, "urn ")) {
-    Exiv2::DataBuf urn(size + 1);
-    io_->readOrThrow(urn.data(), size);
-    urn.write_uint8(size, 0);
     if (currentStream_ == Video)
-      xmpData_["Xmp.video.URN"] = Exiv2::toString(urn.data());
+      xmpData_["Xmp.video.URN"] = readString(*io_, size);
     else if (currentStream_ == Audio)
-      xmpData_["Xmp.audio.URN"] = Exiv2::toString(urn.data());
+      xmpData_["Xmp.audio.URN"] = readString(*io_, size);
   }
 
   else if (equalsQTimeTag(buf, "dcom")) {
-    Exiv2::DataBuf dcom(size + 1);
+    xmpData_["Xmp.video.Compressor"] = readString(*io_, size);
-    io_->readOrThrow(dcom.data(), size);
-    dcom.write_uint8(size, 0);
-    xmpData_["Xmp.video.Compressor"] = Exiv2::toString(dcom.data());
   }
 
   else if (equalsQTimeTag(buf, "smhd")) {
@@ -782,6 +781,7 @@ void QuickTimeVideo::CameraTagsDecoder(size_t size_external) {
     xmpData_["Xmp.video.FocalLength"] = buf.read_uint32(0, littleEndian) / (double)buf2.read_uint32(0, littleEndian);
     io_->seek(static_cast<long>(95), BasicIo::cur);
     io_->readOrThrow(buf.data(), 48);
+    buf.write_uint8(48, 0);
     xmpData_["Xmp.video.Software"] = Exiv2::toString(buf.data());
     io_->readOrThrow(buf.data(), 4);
     xmpData_["Xmp.video.ISO"] = buf.read_uint32(0, littleEndian);
@@ -829,8 +829,8 @@ void QuickTimeVideo::userDataDecoder(size_t size_external) {
 
     else if (equalsQTimeTag(buf, "CNCV") || equalsQTimeTag(buf, "CNFV") || equalsQTimeTag(buf, "CNMN") ||
              equalsQTimeTag(buf, "NCHD") || equalsQTimeTag(buf, "FFMV")) {
-      io_->readOrThrow(buf.data(), size - 8);
+      enforce(tv, Exiv2::ErrorCode::kerCorruptedMetadata);
-      xmpData_[exvGettext(tv->label_)] = Exiv2::toString(buf.data());
+      xmpData_[exvGettext(tv->label_)] = readString(*io_, size - 8);
     }
 
     else if (equalsQTimeTag(buf, "CMbo") || equalsQTimeTag(buf, "Cmbo")) {
@@ -845,15 +845,8 @@ void QuickTimeVideo::userDataDecoder(size_t size_external) {
     }
 
     else if (tv) {
-      const size_t tv_size = size - 12;
-      if (tv_size >= buf.size()) {
-        enforce(tv_size <= io_->size() - io_->tell(), Exiv2::ErrorCode::kerCorruptedMetadata);
-        buf.resize(tv_size + 1);
-      }
       io_->readOrThrow(buf.data(), 4);
-      io_->readOrThrow(buf.data(), tv_size);
+      xmpData_[exvGettext(tv->label_)] = readString(*io_, size - 12);
-      buf.write_uint8(tv_size, 0);  // nul-terminate string
-      xmpData_[exvGettext(tv->label_)] = Exiv2::toString(buf.data());
     }
 
     else if (td)

tests/bugfixes/github/test_issue_2376.py

@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+
+from system_tests import CaseMeta, check_no_ASAN_UBSAN_errors
+
+class issue_2376_QuickTimeVideo_userDataDecoder_null_deref(metaclass=CaseMeta):
+    url      = "https://github.com/Exiv2/exiv2/issues/2376"
+    filename = "$data_path/issue_2376_poc.mp4"
+    commands = ["$exiv2 $filename"]
+    retval   = [1]
+    stderr   = ["""$exiv2_exception_message $filename:
+$kerCorruptedMetadata
+"""]
+    stdout   = [""]

tests/bugfixes/github/test_issue_2377.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+
+from system_tests import CaseMeta, check_no_ASAN_UBSAN_errors
+
+class issue_2377_QuickTimeVideo_userDataDecoder_buffer_overflow(metaclass=CaseMeta):
+    url      = "https://github.com/Exiv2/exiv2/issues/2377"
+    filename = "$data_path/issue_2377_poc.mp4"
+    commands = ["$exiv2 $filename"]
+    retval   = [253]
+    stderr   = ["""$filename: No Exif data found in the file
+"""]
+    stdout   = ["""File name       : $filename
+File size       : 225 Bytes
+MIME type       : video/quicktime
+Image size      : 0 x 0
+"""]
+

tests/regression_tests/test_regression_allfiles.py

@@ -61,6 +61,8 @@ def get_valid_files(data_dir):
         "issue_2340_poc.mp4",
         "issue_2345_poc.mp4",
         "issue_2366_poc.mp4",
+        "issue_2376_poc.mp4",
+        "issue_2377_poc.mp4",
         "2018-01-09-exiv2-crash-001.tiff",
         "cve_2017_1000126_stack-oob-read.webp",
         "exiv2-bug1247.jpg",