[PATCH v2 2/7] nftables: meta: hour: Fix integer overflow error

[Ander Juaristi <a@juaristi.eus>]

This patch fixes an overflow error that would happen when introducing edge times
whose second representation is smaller than the value of the tm_gmtoff field, such
as 00:00.

Signed-off-by: Ander Juaristi <a@juaristi.eus>
---
 src/meta.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/meta.c b/src/meta.c
index 31a86b2..39e551c 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -565,7 +565,7 @@ static void hour_type_print(const struct expr *expr, struct output_ctx *octx)
 		cur_tm = localtime(&ts);
 
 		if (cur_tm)
-			seconds += cur_tm->tm_gmtoff;
+			seconds = (seconds + cur_tm->tm_gmtoff) % 86400;
 
 		__hour_type_print_r(0, 0, seconds, out);
 		nft_print(octx, "\"%s\"", out);
@@ -616,8 +616,12 @@ convert:
 		result = tm.tm_hour * 3600 + tm.tm_min * 60 + tm.tm_sec;
 
 	/* Substract tm_gmtoff to get the current time */
-	if (cur_tm)
-		result -= cur_tm->tm_gmtoff;
+	if (cur_tm) {
+		if (result >= cur_tm->tm_gmtoff)
+			result -= cur_tm->tm_gmtoff;
+		else
+			result = 86400 - cur_tm->tm_gmtoff + result;
+	}
 
 success:
 	*res = constant_expr_alloc(&sym->location, sym->dtype,
-- 
2.17.1