Ticket Change Details
EuroTcl/OpenACS 11 - 12 JULY 2024, VIENNA
Overview

Artifact ID: bbc7698ac8acea6a35b5c2bfb9ac9edb3862d183
Ticket: 6dd5588df68a5afdb421d44cb73b94326efffd3a
tcltls spins forever calling sendto() on flush of a closed connecton
User & Date: anonymous on 2017-09-20 12:47:49
Changes

  1. foundin changed to: "1.7.12"
  2. icomment:
    FreeBSD 11, tcl 8.6.7, tcltls 1.7.12, openssl 1.0.2k.
    
    We have a process that handles a TLS socket and on EOF or error, it exits.
    
    On exit, tcl tries to flush the socket. Sometimes, this will end up hanging forever consuming 100% CPU. truss says:
    
    sendto(10,"\^W\^C\^A\0\240\^V\^E\M-Y\^[\^N"...,165,0,NULL,0) ERR#32 'Broken pipe'
    sendto(10,"\^W\^C\^A\0\240\^V\^E\M-Y\^[\^N"...,165,0,NULL,0) ERR#32 'Broken pipe'
    sendto(10,"\^W\^C\^A\0\240\^V\^E\M-Y\^[\^N"...,165,0,NULL,0) ERR#32 'Broken pipe'
    sendto(10,"\^W\^C\^A\0\240\^V\^E\M-Y\^[\^N"...,165,0,NULL,0) ERR#32 'Broken pipe'
    
    forever; FD 10 is the underlying TCP socket.
    
    gdb says it is hanging here:
    
    (gdb) bt
    #0  0x00000008011d4dfa in _sendto () from /lib/libc.so.7
    #1  0x0000000800e76a6f in pthread_suspend_all_np () from /lib/libthr.so.3
    #2  0x0000000800bf2f71 in TcpOutputProc (instanceData=0x8024fd810, buf=0x802452483 "\027\003\001", toWrite=165, errorCodePtr=0x7fffffffdb7c) at tclUnixSock.c:560
    #3  0x0000000800b63b63 in ChanWrite (chanPtr=0x80c094890, src=0x802452483 "\027\003\001", srcLen=165, errnoPtr=0x7fffffffdb7c) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:517
    #4  0x0000000800b63af7 in Tcl_WriteRaw (chan=0x80c094890, src=0x802452483 "\027\003\001", srcLen=165) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:4039
    #5  0x0000000802cb56ff in BIO_new_tcl () from /usr/local/lib/tls1.7.12/tcltls.so
    #6  0x00000008033b56f8 in BIO_write () from /lib/libcrypto.so.8
    #7  0x0000000802ef6c61 in ssl3_write_pending () from /usr/lib/libssl.so.8
    #8  0x0000000802ef6652 in ssl3_write_bytes () from /usr/lib/libssl.so.8
    #9  0x0000000802edbcf0 in BIO_ssl_shutdown () from /usr/lib/libssl.so.8
    #10 0x00000008033b56f8 in BIO_write () from /lib/libcrypto.so.8
    #11 0x0000000802cb5e1b in Tls_ChannelType () from /usr/local/lib/tls1.7.12/tcltls.so
    #12 0x0000000800b63b63 in ChanWrite (chanPtr=0x80c097f90, 
        src=0x80c38f9f8 "alt\t3943\tclock\t1505832747\tewvel\t153.8\tfpm\t157\thexid\tA0EC3D\tlat\t39.9306\tlon\t-86.1884\tnsvel\t198.0\torigin\t1172\ttype\tmlat_result\n", srcLen=125, 
        errnoPtr=0x7fffffffde38) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:517
    #13 0x0000000800b62c67 in FlushChannel (interp=0x0, chanPtr=0x80c097f90, calledFromAsyncFlush=0) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:2747
    #14 0x0000000800b5f7b4 in Tcl_Close (interp=0x0, chan=0x80c097f90) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:3464
    #15 0x0000000800b5e646 in TclFinalizeIOSubsystem () at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:657
    #16 0x0000000800b2dd7b in FinalizeThread (quick=1) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclEvent.c:1305
    #17 0x0000000800b2dae2 in Tcl_Exit (status=5) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclEvent.c:987
    #18 0x0000000800a62b9d in Tcl_ExitObjCmd (dummy=0x0, interp=0x801c37950, objc=2, objv=0x801c4a868) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclCmdAH.c:1114
    #19 0x0000000800a536aa in Dispatch (data=0x80c319758, interp=0x801c37950, result=0) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclBasic.c:4358
    #20 0x0000000800a4e7f6 in TclNRRunCallbacks (interp=0x801c37950, result=0, rootPtr=0x80c01a540) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclBasic.c:4391
    #21 0x0000000800a50db0 in TclEvalObjEx (interp=0x801c37950, objPtr=0x80c08a0b0, flags=131072, invoker=0x0, word=0) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclBasic.c:5957
    #22 0x0000000800a4df1a in Tcl_EvalObjEx (interp=0x801c37950, objPtr=0x80c08a0b0, flags=131072) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclBasic.c:5938
    #23 0x0000000800b68f40 in TclChannelEventScriptInvoker (clientData=0x80c219cd0, mask=2) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:8866
    #24 0x0000000800b68af9 in Tcl_NotifyChannel (channel=0x80c097f90, mask=2) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclIO.c:8360
    #25 0x0000000800bf2e47 in WrapNotify (clientData=0x8024fd810, mask=2) at tclUnixSock.c:982
    #26 0x0000000800bf7730 in FileHandlerEventProc (evPtr=0x80c2e4a50, flags=-3) at tclUnixNotfy.c:809
    #27 0x0000000800b92d6c in Tcl_ServiceEvent (flags=-3) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclNotify.c:670
    #28 0x0000000800b9326f in Tcl_DoOneEvent (flags=-3) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclNotify.c:967
    #29 0x0000000800b2df6b in Tcl_VwaitObjCmd (clientData=0x0, interp=0x801c37950, objc=2, objv=0x801c4a6b8) at /usr/ports/lang/tcl86/work/tcl8.6.7/generic/tclEvent.c:1413
    
    Some digging with gdb seems to indicate that it is spinning forever in FlushChannel(). TlsOutputProc ("Tls_ChannelType" in the stacktrace above,
    because static function) calls BIO_write() which eventually generates the sendto(). BIO_write() returns with SSL_ERROR_ZERO_RETURN. TlsOutputProc()
    returns 0. FlushChannel() thinks there is more work to do and loops.
    
  3. login: "anonymous"
  4. mimetype: "text/plain"
  5. private_contact changed to: "900fc5ce35b9c7638101bd1f61914637995d3ab3"
  6. severity changed to: "Severe"
  7. status changed to: "Open"
  8. title changed to:
    tcltls spins forever calling sendto() on flush of a closed connecton
    
  9. type changed to: "Code Defect"