From f5ef97c13165542480a6ffdbe6f09f40bbb7cbf1 Mon Sep 17 00:00:00 2001 From: Yuan Tan Date: Mon, 9 Mar 2026 03:41:46 -0700 Subject: netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels [ Upstream commit 329f0b9b48ee6ab59d1ab72fef55fe8c6463a6cf ] IDLETIMER revision 0 rules reuse existing timers by label and always call mod_timer() on timer->timer. If the label was created first by revision 1 with XT_IDLETIMER_ALARM, the object uses alarm timer semantics and timer->timer is never initialized. Reusing that object from revision 0 causes mod_timer() on an uninitialized timer_list, triggering debugobjects warnings and possible panic when panic_on_warn=1. Fix this by rejecting revision 0 rule insertion when an existing timer with the same label is of ALARM type. Fixes: 68983a354a65 ("netfilter: xtables: Add snapshot of hardidletimer target") Co-developed-by: Yifan Wu Signed-off-by: Yifan Wu Co-developed-by: Juefei Pu Signed-off-by: Juefei Pu Signed-off-by: Yuan Tan Signed-off-by: Xin Liu Signed-off-by: Florian Westphal Signed-off-by: Sasha Levin --- net/netfilter/xt_IDLETIMER.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'net') diff --git a/net/netfilter/xt_IDLETIMER.c b/net/netfilter/xt_IDLETIMER.c index d73957592c9d..bb7af92ac82a 100644 --- a/net/netfilter/xt_IDLETIMER.c +++ b/net/netfilter/xt_IDLETIMER.c @@ -318,6 +318,12 @@ static int idletimer_tg_checkentry(const struct xt_tgchk_param *par) info->timer = __idletimer_tg_find_by_label(info->label); if (info->timer) { + if (info->timer->timer_type & XT_IDLETIMER_ALARM) { + pr_debug("Adding/Replacing rule with same label and different timer type is not allowed\n"); + mutex_unlock(&list_mutex); + return -EINVAL; + } + info->timer->refcnt++; mod_timer(&info->timer->timer, secs_to_jiffies(info->timeout) + jiffies); -- cgit v1.2.3