Credit to OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=41438

Replace weird sign-conversion code with a simple static_cast.

Author: kevinbackhouse

src/panasonicmn_int.cpp

@@ -691,17 +691,15 @@ namespace Exiv2 {
 
     std::ostream& PanasonicMakerNote::printAccelerometer(std::ostream& os, const Value& value, const ExifData*)
     {
-        // value is stored as unsigned int, but should be readed as signed int, so manually convert it
-        int i = value.toLong();
-        i = i - ((i & 0x8000) >> 15) * 0xffff;
+        // value is stored as unsigned int, but should be read as int16_t.
+        const int16_t i = static_cast<int16_t>(value.toLong());
         return os << i;
     }  // PanasonicMakerNote::printAccelerometer
 
     std::ostream& PanasonicMakerNote::printRollAngle(std::ostream& os, const Value& value, const ExifData*)
     {
-        // roll angle is stored as signed int, but tag states to be unsigned int
-        int i = value.toLong();
-        i = i - ((i & 0x8000) >> 15) * 0xffff;
+        // value is stored as unsigned int, but should be read as int16_t.
+        const int16_t i = static_cast<int16_t>(value.toLong());
         std::ostringstream oss;
         oss.copyfmt(os);
         os << std::fixed << std::setprecision(1) << i / 10.0;
@@ -712,10 +710,8 @@ namespace Exiv2 {
 
     std::ostream& PanasonicMakerNote::printPitchAngle(std::ostream& os, const Value& value, const ExifData*)
     {
-        // pitch angle is stored as signed int, but tag states to be unsigned int
-        // change sign to be compatible with ExifTool: positive is upwards
-        int i = value.toLong();
-        i = i - ((i & 0x8000) >> 15) * 0xffff;
+        // value is stored as unsigned int, but should be read as int16_t.
+        const int16_t i = static_cast<int16_t>(value.toLong());
         std::ostringstream oss;
         oss.copyfmt(os);
         os << std::fixed << std::setprecision(1) << -i / 10.0;

tests/bugfixes/github/test_issue_2006.py

@@ -16,6 +16,6 @@ class PanasonicMakerPrintAccelerometerIntOverflow(metaclass=CaseMeta):
 Exif.Image.DNGPrivateData                    0x2020     32  80 97 110 97 115 111 110 105 99 32 32 32 0 32 32 255 32 32 32 32 32 255 255 255 32 255 255 198 52 32 32 0
 Exif.MakerNote.Offset                        Long        1  48
 Exif.MakerNote.ByteOrder                     Ascii       3  MM
-Exif.Panasonic.AccelerometerY                SLong       4  2147483425
+Exif.Panasonic.AccelerometerY                SLong       4  -224
 """]
     retval = [0]