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Fix integer overflow in string.IndexOf range validation #128191

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Merged
MihaZupan merged 1 commit into from
May 14, 2026
+34 −4
Merged

Fix integer overflow in string.IndexOf range validation #128191

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9 changes: 5 additions & 4 deletions src/libraries/System.Private.CoreLib/src/System/String.Searching.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -127,7 +127,7 @@ private int IndexOfCharOrdinalIgnoreCase(char value, int startIndex, int count)
ArgumentOutOfRangeException.ThrowIfNegative(startIndex);
ArgumentOutOfRangeException.ThrowIfGreaterThan(startIndex, Length);
ArgumentOutOfRangeException.ThrowIfNegative(count);
ArgumentOutOfRangeException.ThrowIfGreaterThan(startIndex + count, Length);
ArgumentOutOfRangeException.ThrowIfGreaterThan(count, Length - startIndex);

int subIndex;

Expand Down Expand Up @@ -427,9 +427,10 @@ public int IndexOf(Rune value, int startIndex, StringComparison comparisonType)
/// </returns>
public unsafe int IndexOf(Rune value, int startIndex, int count, StringComparison comparisonType)
{
ArgumentOutOfRangeException.ThrowIfLessThan(startIndex, 0);
ArgumentOutOfRangeException.ThrowIfLessThan(count, 0);
ArgumentOutOfRangeException.ThrowIfGreaterThan(startIndex + count, Length);
ArgumentOutOfRangeException.ThrowIfNegative(startIndex);
ArgumentOutOfRangeException.ThrowIfGreaterThan(startIndex, Length);
ArgumentOutOfRangeException.ThrowIfNegative(count);
ArgumentOutOfRangeException.ThrowIfGreaterThan(count, Length - startIndex);

// Convert value to span
ReadOnlySpan<char> valueChars = value.AsSpan(stackalloc char[Rune.MaxUtf16CharsPerRune]);
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29 changes: 29 additions & 0 deletions src/libraries/System.Runtime/tests/System.Runtime.Tests/System/StringTests.cs
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Expand Up @@ -1346,6 +1346,35 @@ public static void ImplicitCast_NullString_ReturnsDefaultSpan()
Assert.True(span == default);
}

[Fact]
public static void IndexOf_Char_OrdinalIgnoreCase_ThrowsArgumentOutOfRangeException()
{
AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => "Hello".IndexOf('o', -1, 0, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => "Hello".IndexOf('o', 6, 0, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf('o', 0, -1, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf('o', 0, 6, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf('o', 3, 3, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf('o', 1, int.MaxValue, StringComparison.OrdinalIgnoreCase));
}

[Fact]
public static void IndexOf_Rune_StartIndexCount_ThrowsArgumentOutOfRangeException()
{
AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => "Hello".IndexOf(new Rune('o'), -1, 0));
AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => "Hello".IndexOf(new Rune('o'), 6, 0));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 0, -1));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 0, 6));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 3, 3));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 1, int.MaxValue));

AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => "Hello".IndexOf(new Rune('o'), -1, 0, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("startIndex", () => "Hello".IndexOf(new Rune('o'), 6, 0, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 0, -1, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 0, 6, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 3, 3, StringComparison.OrdinalIgnoreCase));
AssertExtensions.Throws<ArgumentOutOfRangeException>("count", () => "Hello".IndexOf(new Rune('o'), 1, int.MaxValue, StringComparison.OrdinalIgnoreCase));
}

public static IEnumerable<object[]> IndexOf_SingleLetter_StringComparison_TestData()
{
yield return new object[] { "Hello", 'l', 0, int.MaxValue, StringComparison.Ordinal, null, 2 };
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