Chris Mason
700d8e73d4
sd_dhcp6_client_add_option() and sd_dhcp6_client_add_vendor_option()
store the caller's sd_dhcp6_option in an ordered container whose value
destructor is sd_dhcp6_option_unref, registered via
DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR in dhcp6_option_hash_ops. The
container therefore owns exactly one ref per stored slot.
Both helpers guarded the ref bump only on r < 0:
r = ordered_{hashmap,set}_ensure_put(..., v);
if (r < 0)
return r;
sd_dhcp6_option_ref(v);
ordered_hashmap_ensure_put() (and the ordered_set wrapper) forward the
underlying hashmap_put_boldly tri-state verbatim: 1 on fresh insert, 0
when the identical key+value pair is already stored (no new slot
allocated), <0 on error. The r == 0 path fell through and bumped the
refcount without a corresponding slot.
The extra ref is permanently stranded once the container's destructor
runs. In a long-running networkd that reapplies .network files on
reload this leaks one sd_dhcp6_option allocation per duplicate-add.
Fix by tightening the guard to r <= 0 in both helpers, so
sd_dhcp6_option_ref(v) is reached only on a genuine new slot (r == 1).
Propagate the tri-valued result by returning r from both helpers
instead of a hard-coded constant.
sd_dhcp6_client_add_vendor_option() is a public libsystemd sd_ API;
its success return changes from a constant 1 to {0, 1}.
sd_dhcp6_client_add_option() now also propagates the tri-valued
result (previously a hard-coded 0 on success), giving the two parallel
helpers identical return contracts.
The sole non-fuzz in-tree callers are both in dhcp6_configure()
(src/network/networkd-dhcp6.c), which treat any r >= 0 as success and
do not distinguish 0 from 1, so the contract widening is caller-safe.
Fixes: e7d5fe17db ("DHCP client: make SendOption work for DHCPv6 too.")
Assisted-by: kres (claude-opus-4-7)
Signed-off-by: Chris Mason <clm@meta.com>
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