From 0e991303a8bfde69eee63c841cbdef6b9c57cd30 Mon Sep 17 00:00:00 2001 From: ulfvonbelow Date: Sun, 29 Jan 2023 05:26:48 -0600 Subject: [PATCH] SETU: avoid 64-bit shift on 64-bit value. Shifting a 64-bit value by any more than 63 bits is undefined behavior, apparently - at least, the sanitizers complain about it. The intuitive, obvious result, of course, is for the result to be 0. In this case, when s == 0, x << (64 - s) should result in 0, and (x >> s) should result in x, and the bitwise-or of those two should be x. Which x already was. Perhaps it should be investigated whether (x >> (64 - s)) should actually be (x >> (63 - s)), since 0 <= s < 64. --- src/setu/gnunet-service-setu_strata_estimator.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/src/setu/gnunet-service-setu_strata_estimator.c b/src/setu/gnunet-service-setu_strata_estimator.c index 7981cc847..43ccf3afd 100644 --- a/src/setu/gnunet-service-setu_strata_estimator.c +++ b/src/setu/gnunet-service-setu_strata_estimator.c @@ -85,7 +85,8 @@ salt_key (const struct IBF_Key *k_in, uint64_t x = k_in->key_val; /* rotate ibf key */ - x = (x >> s) | (x << (64 - s)); + if (s > 0) + x = (x >> s) | (x << (64 - s)); k_out->key_val = x; } -- 2.38.1