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Maniphest T2982

Scdaemon, w32 hang if two assuan connections are made in parallel
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Description

To reproduce open two console windows.

In Konsole 1:
gpg-connect-agent

SCD SERIALNO

In Konsole 2:
gpg-connect-agent

SCD SERIALNO

Konsole 2 hangs. All further attempts to connect to scdaemon hang until scdaemon
is killed.
My workaround is to close each connection to the agent in kleopatra before
issuing a new SCD command but that is very fragile imo.

Debug output is uneventful scdaemon loops the message:
2017-03-02 16:34:51 scdaemon[7944] DBG: enter: apdu_get_status: slot=0 hang=0
2017-03-02 16:34:51 scdaemon[7944] DBG: leave: apdu_get_status => sw=0x0 status=7
2017-03-02 16:34:51 scdaemon[7944] npth_pselect failed: Input/output error -
waiting 1s

But it does this even when its not hanging (only one connection active)

I've assigned this to werner because it's windows only.

Event Timeline

• aheinecke added projects: scd, gnupg, Bug Report, gpg4win.Mar 2 2017, 4:37 PM
• aheinecke added subscribers: • gniibe, • aheinecke, • werner.
• werner reassigned this task from • werner to • gniibe.Mar 2 2017, 4:48 PM

I doubt that this is Windows only. On Linux we use our own driver but on
Windows we have to resort to PC/SC. My educated guess is that we are in some
blocking system call which is not npth_unprotected.

• gniibe added a comment.Mar 3 2017, 5:55 AM

Version information, please.

I cannot replicate this on GNU/Linux with PC/SC (by disable-ccid).
Anyway, I am looking into this issue:

npth_pselect failed: Input/output error - waiting 1s
• gniibe added a comment.Mar 3 2017, 6:15 AM

It is selecting FD which is created by gnupg_create_pipe.

• gniibe added a comment.Mar 3 2017, 6:24 AM

It seems npth_eselect is for network FDs.

How about this change?

diff --git a/scd/scdaemon.c b/scd/scdaemon.c
index f7e9f83b5..462ff1b3e 100644

  • a/scd/scdaemon.c

+++ b/scd/scdaemon.c
@@ -1291,7 +1291,7 @@ handle_connections (int listen_fd)

while (npth_sigev_get_pending(&signo))
  handle_signal (signo);

#else

  • ret = npth_eselect (nfd+1, &read_fdset, NULL, NULL, t, NULL, NULL);

+ ret = npth_select (nfd+1, &read_fdset, NULL, NULL, t);

saved_errno = errno;

#endif

• aheinecke added a comment.Mar 3 2017, 9:09 AM

Version was 2.1.19 from the installer built by werner / the speedo system.

I'll try out the patch

• aheinecke added a comment.Mar 3 2017, 10:22 AM

With this patch the log message is different (No such file or directory). Hang
still happens.

2017-03-03 10:21:06 scdaemon[8604] DBG: enter: apdu_get_status: slot=0 hang=0
2017-03-03 10:21:06 scdaemon[8604] DBG: leave: apdu_get_status => sw=0x0 status=7
2017-03-03 10:21:06 scdaemon[8604] npth_pselect failed: No such file or
directory - waiting 1s

• gniibe added a comment.Mar 4 2017, 2:37 AM

This patch tried to fix the issue:
https://git.gnupg.org/cgi-bin/gitweb.cgi?p=gnupg.git;a=commit;h=f9acc7d18bb90f47dafe7e32ae92f567756d6b12

I was wrong that PIPE can be select(2)-ed on Windows. This patch changes the
code so that it uses kill(2) on UNIX and SetEvent on Windows
to break the loop.

• aheinecke added a comment.Mar 13 2017, 11:57 AM

I've tried latest master and it no longer hangs for me.

Thanks. Changing the status to not-released as this is fixed.

• aheinecke closed this task as Resolved.Mar 13 2017, 11:57 AM
• aheinecke added a project: Unreleased.