From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Sun, 29 Jun 2025 11:13:34 +0000 (+0200)
Subject: util: fix endless loop in get_backoff_delta_msec
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f14f2603820e46b1946d8f96eee10c99690aea82;p=thirdparty%2Fkmod.git

util: fix endless loop in get_backoff_delta_msec

If current time t is already past tend, the while loop in
get_backoff_delta_msec never ends.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
Link: https://github.com/kmod-project/kmod/pull/377
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>
---

diff --git a/shared/util.c b/shared/util.c
index 2ffe5647..3d5d179b 100644
--- a/shared/util.c
+++ b/shared/util.c
@@ -540,16 +540,23 @@ unsigned long long get_backoff_delta_msec(unsigned long long tend,
 
 	t = now_msec();
 
-	if (!*delta)
-		*delta = 1;
-	else
-		*delta <<= 1;
+	if (tend <= t) {
+		/* Timeout already reached */
+		*delta = 0;
+	} else {
+		const unsigned long long limit = tend - t;
+
+		if (!*delta)
+			*delta = 1;
+		else
+			*delta <<= 1;
 
-	while (t + *delta > tend)
-		*delta >>= 1;
+		while (*delta > limit)
+			*delta >>= 1;
 
-	if (!*delta && tend > t)
-		*delta = tend - t;
+		if (!*delta)
+			*delta = limit;
+	}
 
 	return t + *delta;
 }