grpc: panic: math/big: mismatched montgomery number lengths

[赖会宁]

Hi, guys，

    I came into trouble of GRPC panic.

    it's tracing stack:

panic: math/big: mismatched montgomery number lengths

goroutine 1787827 [running]:
math/big.nat.montgomery(0x0, 0x0, 0x0, 0xc0056b8f80, 0x10, 0x10, 0xc0056b7400, 0x1a, 0x26, 0xc0008fe0b0, ...)
        /usr/local/go/src/math/big/nat.go:219 +0x507
math/big.nat.expNNMontgomery(0xc0035926c0, 0x40, 0x44, 0xc003592b40, 0x10, 0x45, 0xc000478a00, 0x10, 0x25, 0xc0008fe0b0, ...)
        /usr/local/go/src/math/big/nat.go:1430 +0x327
math/big.nat.expNN(0xc0035926c0, 0x40, 0x44, 0xc003592000, 0x40, 0x44, 0xc000478a00, 0x10, 0x25, 0xc0008fe0b0, ...)
        /usr/local/go/src/math/big/nat.go:1262 +0xa06
math/big.(*Int).Exp(0xc003f733d8, 0xc003f733f8, 0xc0005ca3e0, 0xc0005ca340, 0xc000bbbf60)
        /usr/local/go/src/math/big/int.go:509 +0x1a5
crypto/rsa.decrypt(0x18a0900, 0xc0000e8480, 0xc0005d26c0, 0xc003f733f8, 0xc003f734e8, 0x5d4506, 0x13fd3c0)
        /usr/local/go/src/crypto/rsa/rsa.go:536 +0x19f
crypto/rsa.decryptAndCheck(0x18a0900, 0xc0000e8480, 0xc0005d26c0, 0xc003f73580, 0x100, 0x100, 0xc0053d57a0)
        /usr/local/go/src/crypto/rsa/rsa.go:570 +0x53
crypto/rsa.signPSSWithSalt(0x18a0900, 0xc0000e8480, 0xc0005d26c0, 0x5, 0xc0019e4ac0, 0x20, 0x20, 0xc0019e4ae0, 0x20, 0x20, ...)
        /usr/local/go/src/crypto/rsa/pss.go:217 +0x1c5
crypto/rsa.SignPSS(0x18a0900, 0xc0000e8480, 0xc0005d26c0, 0x5, 0xc0019e4ac0, 0x20, 0x20, 0xc0097e5fe0, 0x40df45, 0x14b45e0, ...)
        /usr/local/go/src/crypto/rsa/pss.go:281 +0x1da
crypto/rsa.(*PrivateKey).Sign(0xc0005d26c0, 0x18a0900, 0xc0000e8480, 0xc0019e4ac0, 0x20, 0x20, 0x18a0920, 0xc0097e5fe0, 0xc005580000, 0x25, ...)
        /usr/local/go/src/crypto/rsa/rsa.go:146 +0x9e
crypto/tls.(*serverHandshakeStateTLS13).sendServerCertificate(0xc003f739e8, 0x0, 0x0)
        /usr/local/go/src/crypto/tls/handshake_server_tls13.go:636 +0x466
crypto/tls.(*serverHandshakeStateTLS13).handshake(0xc003f739e8, 0xc00103ac00, 0x0)
        /usr/local/go/src/crypto/tls/handshake_server_tls13.go:59 +0xd4
crypto/tls.(*Conn).serverHandshake(0xc005ab3c00, 0x0, 0x7f982045c2c0)
        /usr/local/go/src/crypto/tls/handshake_server.go:51 +0xd4
crypto/tls.(*Conn).Handshake(0xc005ab3c00, 0x0, 0x0)
        /usr/local/go/src/crypto/tls/conn.go:1391 +0xc9
google.golang.org/grpc/credentials.(*tlsCreds).ServerHandshake(0xc00063c230, 0x18d9ee0, 0xc001212180, 0x244b200, 0xe9, 0x0, 0x0, 0xc0005176f0, 0x78)
        /var/lib/jenkins/workspace/release/server/pkg/mod/google.golang.org/gr...@v1.32.0/credentials/tls.go:115 +0xdf
google.golang.org/grpc.(*Server).useTransportAuthenticator(0xc000819500, 0x18d9ee0, 0xc001212180, 0x244b200, 0x0, 0x0, 0x244b200, 0xc0058ffbf0, 0xc0492d074d535ba5)
        /var/lib/jenkins/workspace/release/server/pkg/mod/google.golang.org/gr...@v1.32.0/server.go:651 +0x50
google.golang.org/grpc.(*Server).handleRawConn(0xc000819500, 0x18d9ee0, 0xc001212180)
        /var/lib/jenkins/workspace/release/server/pkg/mod/google.golang.org/gr...@v1.32.0/server.go:776 +0xca
google.golang.org/grpc.(*Server).Serve.func3(0xc000819500, 0x18d9ee0, 0xc001212180)
        /var/lib/jenkins/workspace/release/server/pkg/mod/google.golang.org/gr...@v1.32.0/server.go:762 +0x3f
created by google.golang.org/grpc.(*Server).Serve
        /var/lib/jenkins/workspace/release/server/pkg/mod/google.golang.org/gr...@v1.32.0/server.go:761 +0x305

    our go version is 1.16.6, I found no answer by Google search.

    Can anyone help? I'll be very graceful!

[赖会宁]

additional remarks: It happen very  seldom, nearly once one or two weeks.

[dfa...@google.com]

Panics in the standard library should be reported to the go repo: https://github.com/golang/go.  This seems deep enough down that it's not a grpc bug or a user error, but I could be mistaken.