[SCM] Samba Shared Repository - branch master updated - release-4-0-0alpha7-1764-g68c5c6d

Volker Lendecke vlendec at samba.org
Sun May 24 17:19:24 GMT 2009

The branch, master has been updated
       via  68c5c6df0eeae16c56d0abc1b5ec275d18410224 (commit)
      from  e744b0af683b459d5eeaf65f4f8d95b0e10c8ec6 (commit)


- Log -----------------------------------------------------------------
commit 68c5c6df0eeae16c56d0abc1b5ec275d18410224
Author: Volker Lendecke <vl at samba.org>
Date:   Sun May 24 18:57:13 2009 +0200

    Fix a race condition in winbind leading to a panic
    In winbind, we do multiple events in one select round. This needs fixing, but
    as long as we're still using it, for efficiency reasons we need to do that.
    What can happen is the following: We have outgoing data pending for a client,
    	state->fd_event.flags == EVENT_FD_WRITE
    Now a new client comes in, we go through the list of clients to find an idle
    one. The detection for idle clients in remove_idle_client does not take the
    pending data into account. We close the socket that has pending outgoing data,
    the accept(2) one syscall later gives us the same socket.
    In new_connection(), we do a setup_async_read, setting up a read fde. The
    select from before however had found the socket (that we had already closed!!)
    to be writable. In rw_callback we only want to see a readable flag, and we
    panic in the SMB_ASSERT(flags == EVENT_FD_READ).
    Found using
    bin/smbtorture // -U% -N 500 -o 2 local-wbclient


Summary of changes:
 source3/winbindd/winbindd.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

Changeset truncated at 500 lines:

diff --git a/source3/winbindd/winbindd.c b/source3/winbindd/winbindd.c
index 52517b0..e1ce223 100644
--- a/source3/winbindd/winbindd.c
+++ b/source3/winbindd/winbindd.c
@@ -905,6 +905,7 @@ static bool remove_idle_client(void)
 	for (state = winbindd_client_list(); state; state = state->next) {
 		if (state->response.result != WINBINDD_PENDING &&
+		    state->fd_event.flags == EVENT_FD_READ &&
 		    !state->getpwent_state && !state->getgrent_state) {
 			if (!last_access || state->last_access < last_access) {

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