commit | 506f3a7848764bb32e66db7f517284c7dcd3a1f2 | [log] [tgz] |
---|---|---|
author | Pavel Borzenkov <pavel.borzenkov@gmail.com> | Wed Apr 05 09:53:22 2017 +0000 |
committer | John Eikenberry <jae@zhar.net> | Wed Apr 05 14:15:57 2017 -0700 |
tree | 76dfc475ee5640e770c9883dbaf75d2ada5e3afe | |
parent | 9aa225fc15d588a8c781acf9a944186b9f3e7df6 [diff] |
Fix deadlock when using Client + Service over io.Pipe Client + Server might deadlock while being connected via io.Pipe with high request concurrency. The scenario is as follows: - Server is trying to send reply to a previous client's packet and is waiting on Pipe's condvar for the client to read it: 3 0x0000000000460e39 in sync.(*Cond).Wait at /usr/lib/go/src/sync/cond.go:57 4 0x0000000000464519 in io.(*pipe).write at /usr/lib/go/src/io/pipe.go:90 5 0x0000000000464a4c in io.(*PipeWriter).Write at /usr/lib/go/src/io/pipe.go:157 6 0x00000000007a0b66 in go.(*struct { io.Reader; io.WriteCloser }).Write at <autogenerated>:246 7 0x0000000000790cf6 in github.com/pkg/sftp.(*conn).Write at <autogenerated>:3 8 0x000000000073a68d in github.com/pkg/sftp.sendPacket at ./packet.go:130 9 0x000000000073338c in github.com/pkg/sftp.(*conn).sendPacket at ./conn.go:31 10 0x00000000007374b4 in github.com/pkg/sftp.(*packetManager).maybeSendPackets at ./packet-manager.go:87 - Client is sending a new packet and is waiting on Pipe's condvar for the server to read it, while holding clientConn mutex: 5 0x0000000000464a4c in io.(*PipeWriter).Write at /usr/lib/go/src/io/pipe.go:157 6 0x0000000000790cf6 in github.com/pkg/sftp.(*conn).Write at <autogenerated>:3 7 0x000000000073a68d in github.com/pkg/sftp.sendPacket at ./packet.go:130 8 0x000000000073338c in github.com/pkg/sftp.(*conn).sendPacket at ./conn.go:31 9 0x0000000000733bfb in github.com/pkg/sftp.(*clientConn).dispatchRequest at ./conn.go:105 10 0x0000000000733a0b in github.com/pkg/sftp.(*clientConn).sendPacket at ./conn.go:97 - Client's receive loop is processing a reply from the server and is trying to acquire clientConn mutex: 4 0x000000000046108d in sync.(*Mutex).Lock at /usr/lib/go/src/sync/mutex.go:87 5 0x00000000007336cb in github.com/pkg/sftp.(*clientConn).recv at ./conn.go:69 6 0x000000000073350d in github.com/pkg/sftp.(*clientConn).loop at ./conn.go:49 7 0x000000000045ab51 in runtime.goexit at /usr/lib/go/src/runtime/asm_amd64.s:2197 In this scenario neither server nor client can progress. Fix this by releasing clienConn mutex *before* trying to send the packet. Signed-off-by: Pavel Borzenkov <pavel.borzenkov@gmail.com>
The sftp
package provides support for file system operations on remote ssh servers using the SFTP subsystem. It also implements an SFTP server for serving files from the filesystem.
See godoc.org/github.com/pkg/sftp for examples and usage.
The basic operation of the package mirrors the facilities of the os package.
The Walker interface for directory traversal is heavily inspired by Keith Rarick's fs package.
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