batadv_v_elp_start_timer() enqeues a delayed work. The time when it starts
is randomly chosen between (elp_interval - BATADV_JITTER) and
(elp_interval + BATADV_JITTER). The configured elp_interval must therefore
be larger or equal to BATADV_JITTER to avoid that it causes an underflow of
the unsigned integer. If this would happen, then a "fast" ELP interval
would turn into a "day long" delay.
At the same time, it must not be larger than the maximum value the variable
can store.
Fixes: 914db9648ed5 ("batman-adv: Add elp_interval hardif genl configuration")
Signed-off-by: Sven Eckelmann <[email protected]>
---
net/batman-adv/netlink.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index e52f44e7..c8f7a2b2 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -917,9 +917,15 @@ static int batadv_netlink_set_hardif(struct sk_buff *skb,
#ifdef CONFIG_BATMAN_ADV_BATMAN_V
if (info->attrs[BATADV_ATTR_ELP_INTERVAL]) {
- attr = info->attrs[BATADV_ATTR_ELP_INTERVAL];
+ u32 elp_interval;
- atomic_set(&hard_iface->bat_v.elp_interval, nla_get_u32(attr));
+ attr = info->attrs[BATADV_ATTR_ELP_INTERVAL];
+ elp_interval = nla_get_u32(attr);
+
+ elp_interval = min_t(u32, elp_interval, INT_MAX);
+ elp_interval = max_t(u32, elp_interval, BATADV_JITTER);
+
+ atomic_set(&hard_iface->bat_v.elp_interval, elp_interval);
}
if (info->attrs[BATADV_ATTR_THROUGHPUT_OVERRIDE]) {
---
base-commit: 80ee59dc80a8d6287b2af80dad4e7e1c04d3a2cf
change-id: 20260529-jitter-underflow-0a4c44614a25
Best regards,
--
Sven Eckelmann <[email protected]>
