From: Luca Boccassi <luca.boccassi@gmail.com>
Date: Sat, 11 Apr 2026 21:04:37 +0000 (+0100)
Subject: uid-range: add assert to prevent underflow in coalesce loop
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ff102359b7cf767c9c793a163ff34d95370d0107;p=thirdparty%2Fsystemd.git

uid-range: add assert to prevent underflow in coalesce loop

Coverity flags range->n_entries - j as a potential underflow
in the memmove size calculation. Add assert(range->n_entries > 0)
before decrementing n_entries, which holds since the loop condition
guarantees j < n_entries.

CID#1548015

Follow-up for 8dcc66cefc8ab489568c737adcba960756d76a3c
---

diff --git a/src/basic/uid-range.c b/src/basic/uid-range.c
index 3d8f8445c45..62c7d7d928e 100644
--- a/src/basic/uid-range.c
+++ b/src/basic/uid-range.c
@@ -75,6 +75,8 @@ static void uid_range_coalesce(UIDRange *range) {
                         if (range->n_entries > j + 1)
                                 memmove(y, y + 1, sizeof(UIDRangeEntry) * (range->n_entries - j - 1));
 
+                        /* Silence static analyzers, n_entries > 0 since j < n_entries holds in the loop condition */
+                        assert(range->n_entries > 0);
                         range->n_entries--;
 
                         /* Silence static analyzers, j cannot be 0 here since it starts at i + 1, i.e. >= 1 */