From 78b5b6dbd0bb4e5644e798748d186cca88fc523d Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 20 Apr 2022 22:30:22 +0200 Subject: [PATCH] sd-bus: switch to a manual overflow check in sd_bus_track_add_name() This is generally used in a directly client controllable way, hence we should handle ref count overflow gracefully, instead of hitting an assert(). As discussed: https://github.com/systemd/systemd/pull/23099#discussion_r854341850 (cherry picked from commit 7f40cb7c86b0fff3a82096a9499570bad9c19fd2) [msekleta: We've never switched to using track_item_ref/unref introduced in c2d7dd35d2 hence we still had potential undefined behavior related to overflow check and this commit fixes that.] Related: #2084052 --- src/libsystemd/sd-bus/bus-track.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/src/libsystemd/sd-bus/bus-track.c b/src/libsystemd/sd-bus/bus-track.c index 8893f190a1..b818e93bec 100644 --- a/src/libsystemd/sd-bus/bus-track.c +++ b/src/libsystemd/sd-bus/bus-track.c @@ -208,12 +208,16 @@ _public_ int sd_bus_track_add_name(sd_bus_track *track, const char *name) { i = hashmap_get(track->names, name); if (i) { if (track->recursive) { - unsigned k = i->n_ref + 1; + assert(i->n_ref > 0); - if (k < i->n_ref) /* Check for overflow */ + /* Manual oveflow check (instead of a DEFINE_TRIVIAL_REF_FUNC() helper or so), so + * that we can return a proper error, given this is almost always called in a + * directly client controllable way, and thus better should never hit an assertion + * here. */ + if (i->n_ref >= UINT_MAX) return -EOVERFLOW; - i->n_ref = k; + i->n_ref++; } bus_track_remove_from_queue(track);