[mono][interp] Fix null dereference for a calli with a vararg signature - #134133
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Problem: In interp_transform_call() target_method stays NULL for a calli, and every other use of it in the function is guarded by a NULL check. The vararg branch is not, and mono_method_get_signature_checked() dereferences its first argument, so a calli with a vararg signature crashes the transform. Solution: Only re-resolve the signature when target_method is not NULL. Nothing has to be re-resolved for a calli, because csignature is already the call site signature taken from the standalone signature token. Signed-off-by: p.nekrasov@fobos-nt.ru Signed-off-by: morgonf@altlinux.org
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September 17, 2026 12:24
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lewing
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Sep 17, 2026
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This looks like it will fix the missing null check but still fail later. The change needs a working test to verify.
Problem: Guarding the NULL only moves the failure: the call then emits MINT_CALLI, and MINT_INIT_ARGLIST, the first instruction of every vararg method, reads the call site signature from the caller assuming MINT_CALL_VARARG is there. MINT_CALLI is 4 slots wide instead of 6, so a bogus data_items index is used as a MonoMethodSignature *. Solution: Report a vararg calli as not supported next to the existing thiscall check. target_method is only NULL for a calli, so the signature re-resolution needs no guard. Added a test. Signed-off-by: p.nekrasov@fobos-nt.ru Signed-off-by: morgonf@altlinux.org
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You were right: the null check alone just moves the crash into |
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@dotnet-policy-service agree company="Fobos-NT" |
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fix #134129
Only re-resolve the signature when target_method is not NULL
Signed-off-by: p.nekrasov@fobos-nt.ru
Signed-off-by: morgonf@altlinux.org