From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Tue, 22 Apr 2025 17:35:39 +0000 (-0300)
Subject: string: Fix UB on gneric strncmp
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=766ed3827547d5930c95b80c38a056fea358ef6b;p=thirdparty%2Fglibc.git

string: Fix UB on gneric strncmp

Building with ubsan it triggers:

UBSAN: Undefined behaviour in ../string/strncmp.c:103:12 shift exponent 32 is too large for 32-bit type 'int'

Use an unsigned constant literal for MERGE, since op_t is defined
as unsigned.
---

diff --git a/string/strncmp.c b/string/strncmp.c
index 79a21c12a3..746d5acc25 100644
--- a/string/strncmp.c
+++ b/string/strncmp.c
@@ -100,7 +100,7 @@ strncmp_unaligned_loop (const op_t *x1, const op_t *x2, op_t w1, uintptr_t ofs,
 
       /* Load the final word of P1 and align the final partial of P2.  */
       w1 = *x1++;
-      w2 = MERGE (w2b, sh_1, 0, sh_2);
+      w2 = MERGE (w2b, sh_1, 0UL, sh_2);
     }
 
   return final_cmp (w1, w2, n);