Getting a segfault on a bad wifi connection

[ohnorobo]

I was having a wifi issue (my outline connection had stalled silently) where all my connection were hanging. When I tried to run essentially (simplified)

ssURL = "ss://Y2hhY2hhMjAtaWV0Zi1wb2x5MTMwNTprSzdEdHQ0MkJLOE9hRjBKYjdpWGFK@1.1.1.1:9953/?outline=1"
config, err := configurl.ParseConfig(ssURL)
ctx := context.Background()
streamDialer, err := providers.NewStreamDialer(ctx, config.URL.String())
testAddr := net.JoinHostPort("www.rferl.org", "443")
ctx, cancel := context.WithTimeout(ctx, f.TestTimeout)
defer cancel()
testConn, err := dialer.DialStream(ctx, testAddr)

(in reality I was calling go run -C ./x/examples/smart-proxy/ . -v -localAddr=localhost:1080 --transport="" --domain www.rferl.org --config=/Users/2385180/Projects/outline-sdk/x/examples/smart-proxy/config_proxy_only.yaml against https://github.com/Jigsaw-Code/outline-sdk/pull/384/commits/81497869ebade5c51a3231e0a211e74614577980 )

I got an unexpected segfault.

Expected

I should get a timeout error, or some kind of failure (the server doesn't exist anyway)

Actual

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x18 pc=0x1029bd890]

goroutine 41 [running]:
crypto/tls.(*Conn).handshakeContext.func2()
	/usr/local/go/src/crypto/tls/conn.go:1547 +0xa0
created by crypto/tls.(*Conn).handshakeContext in goroutine 1
	/usr/local/go/src/crypto/tls/conn.go:1543 +0x1e8
exit status 2

I'm not certain if it's an error in StreamDialer, or actually in the golang tls code.

I'm not going to look more into replicating this now, but maybe later.

[ohnorobo]

These go lines on my local machine correspond to the following

https://github.com/golang/go/blob/f41fdd962db3264e62ec6acb4a8f5e40d22bdfed/src/crypto/tls/conn.go#L1556 https://github.com/golang/go/blob/f41fdd962db3264e62ec6acb4a8f5e40d22bdfed/src/crypto/tls/conn.go#L1552