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authorVolker Lendecke <vl@samba.org>2011-08-26 16:54:18 +0200
committerVolker Lendecke <vlendec@samba.org>2011-08-26 18:51:24 +0200
commited058f4dc3e059967f3c0538bc220866e9c63588 (patch)
treef9fee3bea1981c73ad526bb386aa2607e4af1c47
parentb72944fea743ec187750239568ba904c7fad653f (diff)
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s3: Fix a winbind race leading to 100% CPU
This fixes a race condition that leads to the winbindd_children list becoming corrupted. It happens when on a busy winbind SIGCHLD is a bit late. Imagine a winbind with multiple requests in the queue for a single child. Child dies, and before the SIGCHLD handler is called we find the socket to be dead. wb_child_request_done is called, receiving an error from wb_simple_trans_recv. It closes the socket. Then immediately the wb_child_request_trigger will do another fork_domain_child before the signal handler is called. This means that we do another fork_domain_child, we have child->sock==-1 at this point. fork_domain_child will do a DLIST_ADD(winbindd_children, child) a second time where the child is already part of that list. This corrupts the list. Then the signal handler kicks in, spinning in for (child = winbindd_children; child != NULL; child = child->next) { forever. Not good. This patch makes sure that both conditions (sock==-1 and not part of the list) for a winbindd_child struct match up. Autobuild-User: Volker Lendecke <vlendec@samba.org> Autobuild-Date: Fri Aug 26 18:51:24 CEST 2011 on sn-devel-104
-rw-r--r--source3/winbindd/winbindd_dual.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/source3/winbindd/winbindd_dual.c b/source3/winbindd/winbindd_dual.c
index 8851b8a258..036ad27213 100644
--- a/source3/winbindd/winbindd_dual.c
+++ b/source3/winbindd/winbindd_dual.c
@@ -43,6 +43,8 @@
extern bool override_logfile;
extern struct winbindd_methods cache_methods;
+static struct winbindd_child *winbindd_children = NULL;
+
/* Read some data from a client connection */
static NTSTATUS child_read_request(struct winbindd_cli_state *state)
@@ -171,6 +173,7 @@ static void wb_child_request_done(struct tevent_req *subreq)
*/
close(state->child->sock);
state->child->sock = -1;
+ DLIST_REMOVE(winbindd_children, state->child);
tevent_req_error(req, err);
return;
}
@@ -489,8 +492,6 @@ void setup_child(struct winbindd_domain *domain, struct winbindd_child *child,
SMB_ASSERT(child->binding_handle != NULL);
}
-static struct winbindd_child *winbindd_children = NULL;
-
void winbind_child_died(pid_t pid)
{
struct winbindd_child *child;