[PATCH] libbpf: fix signed multiplication overflow in hash_combine

["psykose" <alice@ayaya.dev>]

when using -fsanitize=undefined (which flags signed overflow which is
UB), a crash can be reproduced when building the linux kernel with BTF
info.

cast to unsigned first to make the overflow not invoke UB semantics- the
result is the same.

Signed-off-by: psykose <alice@ayaya.dev>
---
 src/btf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/btf.c b/src/btf.c
index 2d0840e..60cd412 100644
--- a/src/btf.c
+++ b/src/btf.c
@@ -3317,7 +3317,7 @@ struct btf_dedup {
 
 static long hash_combine(long h, long value)
 {
-	return h * 31 + value;
+	return (long)((unsigned long)h * 31 + (unsigned long)value);
 }
 
 #define for_each_dedup_cand(d, node, hash) \

base-commit: 42065ea6627ff6e1ab4c65e51042a70fbf30ff7c
-- 
2.45.2