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

bradfitz opened this issue Mar 29, 2017 · 0 comments

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

bradfitz opened this issue Mar 29, 2017 · 0 comments


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@bradfitz bradfitz commented Mar 29, 2017

Backport #19747 ( 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
…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

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

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

Change-Id: Id59430de2e7b5b5117d4903a788863e9d344e53a
Run-TryBot: Brad Fitzpatrick <>
TryBot-Result: Gobot Gobot <>
Reviewed-by: Russ Cox <>
(cherry picked from commit e83fc2e44336423dab94bfe74fad4c4e6a4703b3)
Reviewed-by: Brad Fitzpatrick <>
@bradfitz bradfitz closed this Mar 29, 2017
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