BUG/MEDIUM: mworker: proc_self incorrectly set crashes upon reload
When updating from 2.4 to 2.6, the child->reloads++ instruction changed
place, resulting in a former worker from the 2.4 process, still
identified as a current worker once in 2.6, because its reload counter
is still 0.
Unfortunately this counter is used to chose the mworker_proc structure
that will be used for the new worker.
What happens next, is that the mworker_proc structure of the previous
process is selected, and this one has ipc_fd[1] set to -1, because this
structure was supposed to be in the master.
The process then forks, and mworker_sockpair_register_per_thread() tries
to register ipc_fd[1] which is set to -1, instead of the fd of the new
socketpair.
This patch fixes the issue by checking if child->pid is equal to -1 when
selecting proc_self. This way we could be sure it wasn't a previous
process.
Should fix issue #1785.
This must be backported as far as 2.4 to fix the issue related to the
reload computation difference. However backporting it in every stable
branch will enforce the reload process.
diff --git a/src/haproxy.c b/src/haproxy.c
index 1d0fa33..9ec9639 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -3388,7 +3388,9 @@
ha_notice("New worker (%d) forked\n", ret);
/* find the right mworker_proc */
list_for_each_entry(child, &proc_list, list) {
- if (child->reloads == 0 && child->options & PROC_O_TYPE_WORKER) {
+ if (child->reloads == 0 &&
+ child->options & PROC_O_TYPE_WORKER &&
+ child->pid == -1) {
child->timestamp = now.tv_sec;
child->pid = ret;
child->version = strdup(haproxy_version);
@@ -3482,7 +3484,8 @@
child->ipc_fd[0] = -1;
}
if (child->options & PROC_O_TYPE_WORKER &&
- child->reloads == 0) {
+ child->reloads == 0 &&
+ child->pid == -1) {
/* keep this struct if this is our pid */
proc_self = child;
continue;