image/jpeg: writer crashes with invalid memory address

[deepch]

go version go1.6 linux/amd64

fatal error: fault
[signal 0xb code=0x1 addr=0x18239c3 pc=0x56298b]

goroutine 58010 [running]:
runtime.throw(0x9102a0, 0x5)
/usr/local/go/src/runtime/panic.go:530 +0x90 fp=0xc857d64a08 sp=0xc857d649f0
runtime.sigpanic()
/usr/local/go/src/runtime/sigpanic_unix.go:27 +0x2ab fp=0xc857d64a58 sp=0xc857d64a08
image.(_YCbCr).YCbCrAt(0xc8e2062480, 0x153, 0xf8, 0x263900000000)
/usr/local/go/src/image/ycbcr.go:81 +0x10b fp=0xc857d64ab8 sp=0xc857d64a58
image.(_YCbCr).At(0xc8e2062480, 0x153, 0xf8, 0x0, 0x0)
/usr/local/go/src/image/ycbcr.go:71 +0x45 fp=0xc857d64b00 sp=0xc857d64ab8
image/jpeg.toYCbCr(0x7f2cd0427438, 0xc8e2062480, 0x150, 0xf8, 0xc857d64c60, 0xc857d65360, 0xc857d64f60)
/usr/local/go/src/image/jpeg/writer.go:396 +0xe3 fp=0xc857d64b80 sp=0xc857d64b00
image/jpeg.(*encoder).writeSOS(0xc8200e8900, 0x7f2cd0427438, 0xc8e2062480)
/usr/local/go/src/image/jpeg/writer.go:522 +0x634 fp=0xc857d65598 sp=0xc857d64b80
image/jpeg.Encode(0x7f2cd03e5088, 0xc905042a10, 0x7f2cd0427438, 0xc8e2062480, 0x0, 0x0, 0x0)
/usr/local/go/src/image/jpeg/writer.go:607 +0x483 fp=0xc857d65728 sp=0xc857d65598
main.http_stream_jpeg(0x7f2cda313c70, 0xc820826270, 0xc8dd486380)
/home/deepweb/source-directory/module_http_api.go:131 +0x54c fp=0xc857d65a38 sp=0xc857d65728f

131#

if err := jpeg.Encode(buffer, img, nil); err != nil {
log.Println("unable to encode image.")
}

[ianlancetaylor]

Can you give us a way to recreate the problem ourselves?

Does your program use cgo or the unsafe package?

[deepch]

I will try to recreate the problem. And send you . The daemon is difficult for me to catch her ​​.
Yes my program uses unsafe.

But I think even get nil it should not fall.

[ianlancetaylor]

The program is not getting nil. It is getting a completely invalid address, which should be impossible in ordinary Go code. If you are using the unsafe package, please look very closely at the unsafe code.

[bradfitz]

I'm going to close this until there's something we can do. Feel free to reopen if you have a stand-alone repro, ideally without unsafe.