From 00050ec08cecfda447e1209b388086d76addda3a Mon Sep 17 00:00:00 2001 From: Jenny Guanni Qu Date: Thu, 12 Mar 2026 14:59:49 +0000 Subject: [PATCH] netfilter: xt_time: use unsigned int for monthday bit shift MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The monthday field can be up to 31, and shifting a signed integer 1 by 31 positions (1 << 31) is undefined behavior in C, as the result overflows a 32-bit signed int. Use 1U to ensure well-defined behavior for all valid monthday values. Change the weekday shift to 1U as well for consistency. Fixes: ee4411a1b1e0 ("[NETFILTER]: x_tables: add xt_time match") Reported-by: Klaudia Kloc Reported-by: Dawid MoczadĹ‚o Tested-by: Jenny Guanni Qu Signed-off-by: Jenny Guanni Qu Signed-off-by: Florian Westphal --- net/netfilter/xt_time.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/xt_time.c b/net/netfilter/xt_time.c index 00319d2a54da..d9d74011bb64 100644 --- a/net/netfilter/xt_time.c +++ b/net/netfilter/xt_time.c @@ -223,13 +223,13 @@ time_mt(const struct sk_buff *skb, struct xt_action_param *par) localtime_2(¤t_time, stamp); - if (!(info->weekdays_match & (1 << current_time.weekday))) + if (!(info->weekdays_match & (1U << current_time.weekday))) return false; /* Do not spend time computing monthday if all days match anyway */ if (info->monthdays_match != XT_TIME_ALL_MONTHDAYS) { localtime_3(¤t_time, stamp); - if (!(info->monthdays_match & (1 << current_time.monthday))) + if (!(info->monthdays_match & (1U << current_time.monthday))) return false; }