From dd92a85fb44ff68e075c348176d042448745fac8 Mon Sep 17 00:00:00 2001 From: Steven Luo Date: Mon, 5 Feb 2024 10:22:02 -0800 Subject: [PATCH 1/2] ssh-agent: avoid deadlock when agent process dies before we connect to it gkd_ssh_agent_process_connect() waits for the ssh-agent process to become ready to accept input by entering the main loop while holding self->lock. However, if the ssh-agent process dies before becoming ready, the main loop will call on_child_watch(), which needs to take self->lock, causing a deadlock. Fix this by releasing the lock before entering the main loop. This should prevent a busyloop that's been reported multiple times [1] [2] from lasting forever. [1] https://bugzilla.gnome.org/show_bug.cgi?id=794848 [2] https://bugzilla.redhat.com/show_bug.cgi?id=1841855 (migrated to https://issues.redhat.com/browse/RHEL-9302) --- daemon/ssh-agent/gkd-ssh-agent-process.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/daemon/ssh-agent/gkd-ssh-agent-process.c b/daemon/ssh-agent/gkd-ssh-agent-process.c index d3bb3a7ed..cbf10ffb2 100644 --- a/daemon/ssh-agent/gkd-ssh-agent-process.c +++ b/daemon/ssh-agent/gkd-ssh-agent-process.c @@ -228,8 +228,11 @@ gkd_ssh_agent_process_connect (GkdSshAgentProcess *self, if (started && !self->ready) { source = g_timeout_add_seconds (5, on_timeout, &timedout); - while (!self->ready && !timedout) + while (!self->ready && !timedout) { + g_mutex_unlock (&self->lock); g_main_context_iteration (NULL, FALSE); + g_mutex_lock (&self->lock); + } g_source_remove (source); } -- GitLab From 03ca2228205bfaa7510116142f9beaaf2a682042 Mon Sep 17 00:00:00 2001 From: Steven Luo Date: Mon, 5 Feb 2024 10:29:56 -0800 Subject: [PATCH 2/2] ssh-agent: stop waiting for agent to become ready if it's dead If the ssh-agent process we launch dies before it becomes ready to take input, self->pid will be set to 0 by on_child_watch(). If that happens, there's no point in continuing to wait for the process to become ready. This should avoid an unnecessary five-second wait in cases like [1] or [2]. [1] https://bugzilla.gnome.org/show_bug.cgi?id=794848 [2] https://bugzilla.redhat.com/show_bug.cgi?id=1841855 (migrated to https://issues.redhat.com/browse/RHEL-9302) --- daemon/ssh-agent/gkd-ssh-agent-process.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/daemon/ssh-agent/gkd-ssh-agent-process.c b/daemon/ssh-agent/gkd-ssh-agent-process.c index cbf10ffb2..82e5559fb 100644 --- a/daemon/ssh-agent/gkd-ssh-agent-process.c +++ b/daemon/ssh-agent/gkd-ssh-agent-process.c @@ -226,9 +226,9 @@ gkd_ssh_agent_process_connect (GkdSshAgentProcess *self, started = TRUE; } - if (started && !self->ready) { + if (started && self->pid && !self->ready) { source = g_timeout_add_seconds (5, on_timeout, &timedout); - while (!self->ready && !timedout) { + while (self->pid && !self->ready && !timedout) { g_mutex_unlock (&self->lock); g_main_context_iteration (NULL, FALSE); g_mutex_lock (&self->lock); -- GitLab