From: Olivier Houchard <ohouchard@haproxy.com>
Date: Thu, 3 Sep 2026 12:57:14 +0000 (+0200)
Subject: BUG/MINOR: cli: Make sure two instances of _getsocks don't run
X-Git-Tag: v3.5-dev7~44
X-Git-Url: https://git.kaiwu.me/?a=commitdiff_plain;h=f987d99fce4d44f9db5859b0fac309a6ace28bf5;p=haproxy.git

BUG/MINOR: cli: Make sure two instances of _getsocks don't run

It should never happen, but two instances of _getsocks could run at the
same time, and cause a deadlock, so make sure that never happens by only
allowing one at the same time.
---

diff --git a/src/cli.c b/src/cli.c
index d3569fdc1..b4ba0e365 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -2619,10 +2619,8 @@ static int _getsocks(char **args, char *payload, struct appctx *appctx, void *pr
 	 * a separate file descriptor table.
 	 */
 	nb_foreign = protocol_getsocks_foreign_fds(&foreign_rxs, &foreign_fds);
-	if (nb_foreign < 0) {
-		ha_warning("Failed to allocate memory to transfer other groups' sockets\n");
+	if (nb_foreign < 0)
 		goto out;
-	}
 
 	/*
 	 * First, calculates the total number of FD, so that we can let
diff --git a/src/protocol.c b/src/protocol.c
index eb44f9802..c4c8fa800 100644
--- a/src/protocol.c
+++ b/src/protocol.c
@@ -182,6 +182,8 @@ void protocol_localize_rx_fds(void)
 	HA_SPIN_UNLOCK(PROTO_LOCK, &proto_lock);
 }
 
+static uint getsocks_busy;
+
 /*
  * Collect file descriptor from other thread groups, if they have their
  * own file descriptors table.
@@ -193,6 +195,7 @@ int protocol_getsocks_foreign_fds(struct receiver ***orxs, int **ofds)
 	struct receiver **rxs;
 	int *fds;
 	int nb, filled, done, i;
+	uint idle = 0;
 
 	*orxs = NULL;
 	*ofds = NULL;
@@ -200,6 +203,14 @@ int protocol_getsocks_foreign_fds(struct receiver ***orxs, int **ofds)
 	if (MAX_TGROUPS < 2 || !(global.tune.options & GTUNE_NO_TG_FD_SHARING) || global.nbtgroups < 2)
 		return 0;
 
+	/* a concurrent collection would overwrite the per-receiver slots, and
+	 * two of them blocking their groups' runner threads would deadlock.
+	 */
+	if (!HA_ATOMIC_CAS(&getsocks_busy, &idle, 1)) {
+		ha_warning("_getsocks: a collection is already in progress, giving up.\n");
+		return -1;
+	}
+
 	/* first pass: count the candidates */
 	nb = 0;
 	HA_SPIN_LOCK(PROTO_LOCK, &proto_lock);
@@ -214,14 +225,18 @@ int protocol_getsocks_foreign_fds(struct receiver ***orxs, int **ofds)
 	}
 	HA_SPIN_UNLOCK(PROTO_LOCK, &proto_lock);
 
-	if (!nb)
+	if (!nb) {
+		HA_ATOMIC_STORE(&getsocks_busy, 0);
 		return 0;
+	}
 
 	rxs = calloc(nb, sizeof(*rxs));
 	fds = calloc(nb, sizeof(*fds));
 	if (!rxs || !fds) {
 		free(rxs);
 		free(fds);
+		HA_ATOMIC_STORE(&getsocks_busy, 0);
+		ha_warning("Failed to allocate memory to transfer other groups' sockets\n");
 		return -1;
 	}
 
@@ -282,6 +297,8 @@ int protocol_getsocks_foreign_fds(struct receiver ***orxs, int **ofds)
 		done++;
 	}
 
+	HA_ATOMIC_STORE(&getsocks_busy, 0);
+
 	if (!done) {
 		free(rxs);
 		free(fds);