From e42d953f47e2339c03e663cdff5015d61873dcea Mon Sep 17 00:00:00 2001
From: Lars Vahlenberg <lars.vahlenberg@gmail.com>
Date: Wed, 10 Jul 2024 19:53:32 +0200
Subject: [PATCH] Check crc on tar header

---
 .../Common/Tar/Headers/TarHeader.cs              |   7 +++++++
 tests/SharpCompress.Test/Tar/TarArchiveTests.cs  |  11 +++++++++--
 tests/TestArchives/Archives/false.positive.tar   | Bin 0 -> 1024 bytes
 3 files changed, 16 insertions(+), 2 deletions(-)
 create mode 100644 tests/TestArchives/Archives/false.positive.tar

diff --git a/src/SharpCompress/Common/Tar/Headers/TarHeader.cs b/src/SharpCompress/Common/Tar/Headers/TarHeader.cs
index e9aa343c..510d38a0 100644
--- a/src/SharpCompress/Common/Tar/Headers/TarHeader.cs
+++ b/src/SharpCompress/Common/Tar/Headers/TarHeader.cs
@@ -134,6 +134,13 @@ internal sealed class TarHeader
             hasLongValue = false;
         } while (hasLongValue);
 
+        var crc = ReadAsciiInt64Base8(buffer, 148, 7);
+
+        if (crc != RecalculateChecksum(buffer))
+        {
+            return false;
+        }
+
         Name = longName ?? ArchiveEncoding.Decode(buffer, 0, 100).TrimNulls();
         EntryType = entryType;
         Size = ReadSize(buffer);
diff --git a/tests/SharpCompress.Test/Tar/TarArchiveTests.cs b/tests/SharpCompress.Test/Tar/TarArchiveTests.cs
index bbf96c00..6a8f3294 100644
--- a/tests/SharpCompress.Test/Tar/TarArchiveTests.cs
+++ b/tests/SharpCompress.Test/Tar/TarArchiveTests.cs
@@ -217,8 +217,7 @@ public class TarArchiveTests : ArchiveTests
     {
         var archiveFullPath = Path.Combine(TEST_ARCHIVES_PATH, "Tar.Empty.tar");
         using Stream stream = File.OpenRead(archiveFullPath);
-        using var archive = ArchiveFactory.Open(stream);
-        Assert.True(archive.Type == ArchiveType.Tar);
+        Assert.Throws<InvalidOperationException>(() => ArchiveFactory.Open(stream));
     }
 
     [Theory]
@@ -287,4 +286,12 @@ public class TarArchiveTests : ArchiveTests
 
         Assert.Equal(2, numberOfEntries);
     }
+
+    [Fact]
+    public void Tar_Detect_Test()
+    {
+        var isTar = TarArchive.IsTarFile(Path.Combine(TEST_ARCHIVES_PATH, "false.positive.tar"));
+
+        Assert.False(isTar);
+    }
 }
diff --git a/tests/TestArchives/Archives/false.positive.tar b/tests/TestArchives/Archives/false.positive.tar
new file mode 100644
index 0000000000000000000000000000000000000000..db91a2ff2657cb03d7538bb306d0b9816837fb6a
GIT binary patch
literal 1024
zcmdmZ+NXyB2)IE65X`MMWncu-s$d=im<?ibvM?}Q1k%h5tPD0{P)Q)g55!(f3=C`x
z%y9@&+OSxe+2HPh*#L6uC?G!s<bYaPffyLQ48Uk)aCT*2*asA7wFh#50K}F6(jYYg
WPz+Lw4mg1kflVA;-6(%>g#Z90vk52w

literal 0
HcmV?d00001