[gnunet] 25/28: SETU: avoid 64-bit shift on 64-bit value.

[gnunet]

This is an automated email from the git hooks/post-receive script.

martin-schanzenbach pushed a commit to branch master
in repository gnunet.

commit 7341cdfb5bef6abaf4e12c91d016a940e201e8b7
Author: ulfvonbelow <strilen@tilde.club>
AuthorDate: Sun Jan 29 05:26:48 2023 -0600

    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.
    
    Signed-off-by: Martin Schanzenbach <schanzen@gnunet.org>
---
 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;
 }
 

-- 
To stop receiving notification emails like this one, please contact
gnunet@gnunet.org.