[release/10.0] JIT: fix AV caused by JIT#121499
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steveisok merged 1 commit intorelease/10.0from Nov 12, 2025
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The JIT attempts to deduce a class handle for the return type of TYP_REF calls, and almost always succeeds. However System.Array.Clone is special cased to return the type of its argument, and this argument may be a byref indir without a known managed type, so this deduction may fail. This causes the JIT to pass a null handle into the VM. Cope with this by setting the type instead of updating the type, if we discover it later via inlining. Closes #120522.
This was referenced Nov 10, 2025
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@EgorBo can you PTAL |
EgorBo
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Nov 11, 2025
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/ba-g Known issues #112633 dotnet/dnceng#6408 dotnet/dnceng#1883 |
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Backport of #120575 to release/10.0
/cc @AndyAyersMS
Customer Impact
Reported by customer in #120522
Regression
Similar problem exists in .NET 8 and .NET 9. I intend to backport this fix there if we fix this in .NET 10.
Testing
Verified on the test case from the issue.
Risk
Low. The JIT special cases return type deductions for
Array.Clone, and this issue only triggers if the argument toArray.Cloneis a byref. The fix is a bit more general but is mainly defensive, handling cases where return type deductions fail.