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net/http: Hijack deadlock if system clock is 1970 (backport) #19771

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bradfitz opened this issue Mar 29, 2017 · 0 comments

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commented Mar 29, 2017

Backport #19747 (https://golang.org/cl/38785) to Go 1.8.1

@bradfitz bradfitz added this to the Go1.8.1 milestone Mar 29, 2017

@bradfitz bradfitz self-assigned this Mar 29, 2017

gopherbot pushed a commit that referenced this issue Mar 29, 2017

[release-branch.go1.8] net, net/http: adjust time-in-past constant ev…
…en earlier

The aLongTimeAgo time value in net and net/http is used to cancel
in-flight read and writes. It was set to time.Unix(233431200, 0)
which seemed like far enough in the past.

But Raspberry Pis, lacking a real time clock, had to spoil the fun and
boot in 1970 at the Unix epoch time, breaking assumptions in net and
net/http.

So change aLongTimeAgo to time.Unix(1, 0), which seems like the
earliest safe value. I don't trust subsecond values on all operating
systems, and I don't trust the Unix zero time. The Raspberry Pis do
advance their clock at least. And the reported problem was that Hijack
on a ResponseWriter hung forever, waiting for the connection read
operation to finish. So now, even if kernel + userspace boots in under
a second (unlikely), the Hijack will just have to wait for up to a
second.

Updates #19747
Fixes #19771 (backport to Go 1.8.x)

Change-Id: Id59430de2e7b5b5117d4903a788863e9d344e53a
Reviewed-on: https://go-review.googlesource.com/38785
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
(cherry picked from commit e83fc2e44336423dab94bfe74fad4c4e6a4703b3)
Reviewed-on: https://go-review.googlesource.com/38786
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

@bradfitz bradfitz closed this Mar 29, 2017

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