From ff1c803279cfc8bdee8f2e13798cd3e4d99762c0 Mon Sep 17 00:00:00 2001 From: Christopher Faulet Date: Thu, 20 Jul 2023 14:53:50 +0200 Subject: [PATCH] BUG/MEDIUM: listener: Acquire proxy's lock in relax_listener() if necessary Listener functions must follow a common locking pattern: 1. Get the proxy's lock if necessary 2. Get the protocol's lock if necessary 3. Get the listener's lock if necessary We must take care to respect this order to avoid any ABBA issue. However, an issue was introduced in the commit bcad7e631 ("MINOR: listener: add relax_listener() function"). relax_listener() gets the lisener's lock and if resume_listener() is called, the proxy's lock is then acquired. So to fix the issue, the proxy's lock is first acquired in relax_listener(), if necessary. This patch should fix the issue #2222. It must be backported as far as 2.4 because the above commit is marked to be backported there. --- src/listener.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/listener.c b/src/listener.c index a1160da76..70d13ea84 100644 --- a/src/listener.c +++ b/src/listener.c @@ -633,18 +633,26 @@ int resume_listener(struct listener *l, int lpx, int lli) */ int relax_listener(struct listener *l, int lpx, int lli) { + struct proxy *px = l->bind_conf->frontend; int ret = 1; + if (!lpx && px) + HA_RWLOCK_WRLOCK(PROXY_LOCK, &px->lock); + if (!lli) HA_RWLOCK_WRLOCK(LISTENER_LOCK, &l->lock); if (l->state != LI_FULL && l->state != LI_LIMITED) goto end; /* listener may be suspended or even stopped */ - ret = resume_listener(l, lpx, 1); + ret = resume_listener(l, 1, 1); end: if (!lli) HA_RWLOCK_WRUNLOCK(LISTENER_LOCK, &l->lock); + + if (!lpx && px) + HA_RWLOCK_WRUNLOCK(PROXY_LOCK, &px->lock); + return ret; }