From 55768a20adaa1b5a9158cf3cfdc2f8733ddf43ab Mon Sep 17 00:00:00 2001 From: Tarek Mahmoud Sayed Date: Fri, 10 Feb 2023 22:18:48 +0000 Subject: [PATCH] Fix TimeZone when reading invalid TZ files Add validation to TZ Ids. --- .../src/Resources/Strings.resx | 6 +++ .../System/TimeZoneInfo.Unix.NonAndroid.cs | 48 ++++++++++++++++++- .../tests/System/TimeZoneInfoTests.cs | 5 ++ 3 files changed, 57 insertions(+), 2 deletions(-) diff --git a/src/libraries/System.Private.CoreLib/src/Resources/Strings.resx b/src/libraries/System.Private.CoreLib/src/Resources/Strings.resx index 9b8eee748e7132..66a83c4b379817 100644 --- a/src/libraries/System.Private.CoreLib/src/Resources/Strings.resx +++ b/src/libraries/System.Private.CoreLib/src/Resources/Strings.resx @@ -2603,6 +2603,9 @@ Common Language Runtime detected an invalid program. + + The time zone ID '{0}' is invalid. + The time zone ID '{0}' was found on the local computer, but the file at '{1}' was corrupt. @@ -2627,6 +2630,9 @@ This assembly does not have a file table because it was loaded from memory. + + Unsupported unseekable file. + Unable to read beyond the end of the stream. diff --git a/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.NonAndroid.cs b/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.NonAndroid.cs index a9d6c462610fe6..16be46b6c01117 100644 --- a/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.NonAndroid.cs +++ b/src/libraries/System.Private.CoreLib/src/System/TimeZoneInfo.Unix.NonAndroid.cs @@ -24,17 +24,61 @@ private static TimeZoneInfo GetLocalTimeZoneCore() return GetLocalTimeZoneFromTzFile(); } + private static byte[] ReadAllBytesFromSeekableNonZeroSizeFile(string path, int maxFileSize) + { + using FileStream fs = File.OpenRead(path); + if (!fs.CanSeek) + { + throw new IOException(SR.IO_UnseekableFile); + } + + if (fs.Length == 0 || fs.Length > maxFileSize) + { + throw new IOException(fs.Length == 0 ? SR.IO_InvalidReadLength : SR.IO_FileTooLong); + } + + byte[] bytes = new byte[fs.Length]; + fs.ReadExactly(bytes, 0, bytes.Length); + return bytes; + } + + // Bitmap covering the ASCII range. The bits is set for the characters [a-z], [A-Z], [0-9], '/', '-', and '_'. + private static byte[] asciiBitmap = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0xA8, 0xFF, 0x03, 0xFE, 0xFF, 0xFF, 0x87, 0xFE, 0xFF, 0xFF, 0x07 }; + private static bool IdContainsAnyDisallowedChars(string zoneId) + { + for (int i = 0; i < zoneId.Length; i++) + { + int c = zoneId[i]; + if (c > 0x7F) + { + return true; + } + int value = c >> 3; + if ((asciiBitmap[value] & (ulong)(1UL << (c - (value << 3)))) == 0) + { + return true; + } + } + return false; + } + private static TimeZoneInfoResult TryGetTimeZoneFromLocalMachineCore(string id, out TimeZoneInfo? value, out Exception? e) { value = null; e = null; + if (Path.IsPathRooted(id) || IdContainsAnyDisallowedChars(id)) + { + e = new TimeZoneNotFoundException(SR.Format(SR.InvalidTimeZone_InvalidId, id)); + return TimeZoneInfoResult.TimeZoneNotFoundException; + } + string timeZoneDirectory = GetTimeZoneDirectory(); string timeZoneFilePath = Path.Combine(timeZoneDirectory, id); byte[] rawData; try { - rawData = File.ReadAllBytes(timeZoneFilePath); + rawData = ReadAllBytesFromSeekableNonZeroSizeFile(timeZoneFilePath, maxFileSize: 20 * 1024 * 1024 /* 20 MB */); // timezone files usually less than 1 MB. } catch (UnauthorizedAccessException ex) { @@ -51,7 +95,7 @@ private static TimeZoneInfoResult TryGetTimeZoneFromLocalMachineCore(string id, e = ex; return TimeZoneInfoResult.TimeZoneNotFoundException; } - catch (IOException ex) + catch (Exception ex) when (ex is IOException || ex is OutOfMemoryException) { e = new InvalidTimeZoneException(SR.Format(SR.InvalidTimeZone_InvalidFileData, id, timeZoneFilePath), ex); return TimeZoneInfoResult.InvalidTimeZoneException; diff --git a/src/libraries/System.Runtime/tests/System/TimeZoneInfoTests.cs b/src/libraries/System.Runtime/tests/System/TimeZoneInfoTests.cs index ea3b1bfdef1a6c..8a8eb06bc81204 100644 --- a/src/libraries/System.Runtime/tests/System/TimeZoneInfoTests.cs +++ b/src/libraries/System.Runtime/tests/System/TimeZoneInfoTests.cs @@ -2083,6 +2083,11 @@ public static IEnumerable ConvertTime_DateTimeOffset_InvalidDestinatio yield return new object[] { s_strPacific + "\\Display" }; yield return new object[] { s_strPacific + "\n" }; // no trailing newline yield return new object[] { new string('a', 100) }; // long string + yield return new object[] { "/dev/random" }; + yield return new object[] { "Invalid Id" }; + yield return new object[] { "Invalid/Invalid" }; + yield return new object[] { $"./{s_strPacific}" }; + yield return new object[] { $"{s_strPacific}/../{s_strPacific}" }; } [Theory]