net: TestFilePacketConn fails on Scaleway #10730

bradfitz · 2015-05-06T23:15:55Z

On a Scaleway ARM host (where we're trying to move the ARM builders), the net package fails with:

--- FAIL: TestFilePacketConn (0.00s)
        file_test.go:113: write ip 127.0.0.1->127.0.0.1: sendto: bad address

Debug:

root@scw-105acb:~/go/src# cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=14.10
DISTRIB_CODENAME=utopic
DISTRIB_DESCRIPTION="Ubuntu 14.10"
root@scw-105acb:~/go/src# ifconfig 
docker0   Link encap:Ethernet  HWaddr 56:84:7a:fe:97:99  
          inet addr:172.17.42.1  Bcast:0.0.0.0  Mask:255.255.0.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

eth0      Link encap:Ethernet  HWaddr 00:07:cb:03:76:44  
          inet addr:10.1.34.160  Bcast:10.1.35.255  Mask:255.255.254.0
          inet6 addr: fe80::207:cbff:fe03:7644/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:357998 errors:0 dropped:0 overruns:0 frame:0
          TX packets:108129 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:532 
          RX bytes:352772865 (352.7 MB)  TX bytes:2078718437 (2.0 GB)
          Interrupt:24 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:20563 errors:0 dropped:0 overruns:0 frame:0
          TX packets:20563 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:66891220 (66.8 MB)  TX bytes:66891220 (66.8 MB)

root@scw-105acb:~/go/src# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         10.1.34.1       0.0.0.0         UG    0      0        0 eth0
10.1.34.0       0.0.0.0         255.255.254.0   U     0      0        0 eth0
172.17.0.0      0.0.0.0         255.255.0.0     U     0      0        0 docker0

Note that this machine has a Docker daemon running, but I'm not yet running the build inside a container. This failure was from running on the host machine, as part of evaluating the speed of these machines.

/cc @mikioh, @davecheney, @crawshaw, @adg

The text was updated successfully, but these errors were encountered:

bradfitz · 2015-05-06T23:42:52Z

And the strace:

[pid 15756] socket(PF_INET, SOCK_RAW|SOCK_CLOEXEC|SOCK_NONBLOCK, IPPROTO_ICMP) = 3
[pid 15756] setsockopt(3, SOL_SOCKET, SO_BROADCAST, [1], 4) = 0
[pid 15756] bind(3, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("127.0.0.1")}, 16) = 0
[pid 15756] epoll_ctl(4, EPOLL_CTL_ADD, 3, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=3058795512, u64=3058795512}}) = 0
[pid 15756] getsockname(3, {sa_family=AF_INET, sin_port=htons(1), sin_addr=inet_addr("127.0.0.1")}, [16]) = 0
[pid 15756] getpeername(3, 0x10649bac, [112]) = -1 ENOTCONN (Transport endpoint is not connected)
[pid 15756] fcntl(3, F_DUPFD_CLOEXEC, 0) = 5
[pid 15756] fcntl(5, F_GETFL)           = 0x802 (flags O_RDWR|O_NONBLOCK)
[pid 15756] fcntl(5, F_SETFL, O_RDWR)   = 0
[pid 15756] fcntl(5, F_DUPFD_CLOEXEC, 0) = 6
[pid 15756] fcntl(6, F_GETFL)           = 0x2 (flags O_RDWR)
[pid 15756] fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK) = 0
[pid 15756] getsockopt(6, SOL_SOCKET, SO_TYPE, [3], [4]) = 0
[pid 15756] getsockname(6, {sa_family=AF_INET, sin_port=htons(1), sin_addr=inet_addr("127.0.0.1")}, [16]) = 0
[pid 15756] getpeername(6, 0x10649bdc, [112]) = -1 ENOTCONN (Transport endpoint is not connected)
[pid 15756] epoll_ctl(4, EPOLL_CTL_ADD, 6, {EPOLLIN|EPOLLOUT|EPOLLRDHUP|EPOLLET, {u32=3058795392, u64=3058795392}}) = 0
[pid 15756] sendto(6, "", 0, 0, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EFAULT (Bad address)
[pid 15756] clock_gettime(CLOCK_REALTIME, {1430954968, 213392054}) = 0
[pid 15756] write(1, "--- FAIL: TestFilePacketConn (0."..., 529--- FAIL: TestFilePacketConn (0.04s)
        file_test.go:113: write ip 127.0.0.1->127.0.0.1: sendto: bad address
) = 529
[pid 15756] write(1, "FAIL\n", 5FAIL
)       = 5
[pid 15756] close(3)                    = 0
[pid 15756] exit_group(1)               = ?
[pid 15758] +++ exited with 1 +++
[pid 15757] +++ exited with 1 +++
+++ exited with 1 +++

bradfitz · 2015-05-06T23:46:58Z

The sendto EFAULT is seems wrong.

       EFAULT An invalid user space address was specified for an argument.

The man page says:

       ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
                      const struct sockaddr *dest_addr, socklen_t addrlen);

Is a NULL buf *void okay, even with len 0?

bradfitz · 2015-05-07T00:00:21Z

Actually, the syscall package already tries hard to avoid a NULL *void:

// Single-word zero for use when we need a valid pointer to 0 bytes.                                                
// See mksyscall.pl.                                                                                                
var _zero uintptr

func sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error) {
        var _p0 unsafe.Pointer
        if len(buf) > 0 {
                _p0 = unsafe.Pointer(&buf[0])
        } else {
                _p0 = unsafe.Pointer(&_zero)
        }
        _, _, e1 := Syscall6(SYS_SENDTO, uintptr(s), uintptr(_p0), uintptr(len(buf)), uintptr(flags), uintptr(to), uintptr(addrlen))
        if e1 != 0 {
                err = errnoErr(e1)
        }
        return
}

... yet &_zero (which should be non-nil) ends up as zero according to the strace.

Is Syscall6 doing the right thing?

This machine FWIW has 4 of these:

# cat /proc/cpuinfo 
processor       : 0
model name      : ARMv7 Processor rev 2 (v7l)
BogoMIPS        : 1332.01
Features        : half thumb fastmult vfp edsp thumbee vfpv3 tls idiva idivt vfpd32 lpae 
CPU implementer : 0x56
CPU architecture: 7
CPU variant     : 0x2
CPU part        : 0x584
CPU revision    : 2

/cc @minux @ianlancetaylor @rsc @davecheney @josharian

mikioh · 2015-05-07T00:11:18Z

Maybe dup of #7299? (correction s/7229/7299)

bradfitz · 2015-05-07T00:15:06Z

No, I just can't read. The buf pointer is indeed non-zero. I was off by one reading all the empty values. And strace in raw mode (as well as some printlns in the syscall package) confirms:

[pid 16133] write(2, "sendto zero ", 12sendto zero ) = 12
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "0x3af964", 80x3af964)     = 8
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "0x3af964", 80x3af964)     = 8
[pid 16133] write(2, "\n", 1
)           = 1
[pid 16133] write(2, "sendto ", 7sendto )      = 7
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "290", 3290)          = 3
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "6", 16)            = 1
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "3864932", 73864932)      = 7
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "0", 10)            = 1
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "0", 10)            = 1
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "275330280", 9275330280)    = 9
[pid 16133] write(2, " ", 1 )            = 1
[pid 16133] write(2, "16", 216)           = 2
[pid 16133] write(2, "\n", 1
)           = 1
[pid 16133] sendto(0x6, 0x3af964, 0, 0, 0x106934e8, 0x10) = -1 (errno 14)

So it's only len and flags which are zero.

Still no clue about the EFAULT, though.

minux · 2015-05-07T00:16:47Z

The syscall code is correct as far as I can see. Note that the kernel is not complaining about NULL buf. EFAULT must be for something else. sendto(6, "", 0, 0, {sa_family=AF_INET, sin_port=htons(0), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EFAULT (Bad address) Note that the 2nd argument is "", not NULL. strace(1) treats the buffer as a pointer to a string. as _zero is declared as `var _zero uintptr`, it's content defaults to zero, so the address is pointing to a memory region consists solely of NUL bytes, so strace display that as an empty string "".

mikioh · 2015-05-07T00:25:48Z

Ah, if the error you are seeing is only

write ip 127.0.0.1->127.0.0.1: sendto: bad address

I'll take this issue. Seems like it just happens in the top/middle-half of ICMP stack.

bradfitz · 2015-05-07T00:28:11Z

Not sure what that means but happy for a fix. (ICMP has three halves? :))

mikioh · 2015-05-07T01:17:03Z

As a matter of convenience, I usually think that it consists of socket-interface adaptation layer (or service access point layer), protocol layer and transport (in this case IP) adaptation layer. I believe that the root cause of this issue is just passing a corrupted ICMP packet to the kernel. Certainly the 4-year-old test cases need to be updated for the recent restricted kernels.

In addition, from Go 1.5, the full stack test cases for IPConn have been moved to the following:
golang.org/x/net/ipv4
golang.org/x/net/ipv6
golang.org/x/net/icmp

I'm happy if buildbots can support to run tests in x/net with administrator privilege eventually.

bradfitz · 2015-05-07T02:18:12Z

I'm going to just delete that test for now, then. You can re-enable it later when you identify how the test is broken.

bradfitz · 2015-05-07T02:24:46Z

Kernel is 3.19.1-181, FWIW.

To be fixed later. Updates #10730 Change-Id: Icac19f48c9e035dce192c97943b77b60411a3ea2 Reviewed-on: https://go-review.googlesource.com/9797 Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>

moul · 2015-05-11T12:25:31Z

Subscribing, I'm from the Scaleway team

gopherbot · 2015-05-14T09:00:31Z

CL https://golang.org/cl/10090 mentions this issue.

gopherbot · 2015-05-15T07:00:25Z

CL https://golang.org/cl/10134 mentions this issue.

This change splits the existing ping test into non-privileged and privileged tests to cover IPConn full stack test on behalf of the standard library. Updates golang/go#10730. Change-Id: I5d2e00c0b42b857045414eb8e0efca393967742e Reviewed-on: https://go-review.googlesource.com/10090 Reviewed-by: Ian Lance Taylor <iant@golang.org>

gopherbot · 2015-12-07T09:01:27Z

CL https://golang.org/cl/17476 mentions this issue.

bradfitz added this to the Go1.5 milestone May 6, 2015

adg changed the title ~~net:~~ net: TestFilePacketConn fails on Scaleway May 6, 2015

mikioh self-assigned this May 7, 2015

mikioh added the Testing label May 8, 2015

mikioh modified the milestones: Go1.6, Go1.5 May 21, 2015

mikioh removed their assignment Sep 23, 2015

mikioh closed this as completed in 6a1c2a5 Dec 14, 2015

golang locked and limited conversation to collaborators Dec 14, 2016

gopherbot added the FrozenDueToAge label Dec 14, 2016

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net: TestFilePacketConn fails on Scaleway #10730

net: TestFilePacketConn fails on Scaleway #10730

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net: TestFilePacketConn fails on Scaleway #10730

net: TestFilePacketConn fails on Scaleway #10730

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