Detect overflow when decoding DER variable-length integers#9537
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basavaraj-sm05 wants to merge 1 commit into
Open
Detect overflow when decoding DER variable-length integers#9537basavaraj-sm05 wants to merge 1 commit into
basavaraj-sm05 wants to merge 1 commit into
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DerReader decodes ASN.1 variable-length integers for OBJECT IDENTIFIER subidentifiers and high-number tags, building the value up with a shift left of 7 per continuation byte. That accumulation had no overflow guard (it carried a
// TODO: detect overflow), so a subidentifier padded with enough continuation bytes silently wraps a Long and the shift can flip the sign. I ran into it decoding a certificate whose OID had an over-long arc: instead of rejecting the input,readObjectIdentifierhanded back a bogus arc like2.9223372036854775728produced by the wrapped arithmetic. Since these bytes come straight off an untrusted certificate, quietly turning a malformed OID into a real-looking one seemed worth closing off. This throws aProtocolExceptiononce the running value no longer fits in a Long, the same way the length decoder just above already rejects a length pastLong.MAX_VALUE. Values up toLong.MAX_VALUEstill decode exactly as before, and there's a regression test for the overflowing case.