From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Fri, 2 May 2025 18:41:00 +0000 (-0300)
Subject: math: Fix UB in ldbl-128 llroundl
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e5387c94938f81882bc82c73348a14b77d8f5f8a;p=thirdparty%2Fglibc.git

math: Fix UB in ldbl-128 llroundl

Building with --enable-ubasn triggers:

$ math/test-float128-llround
testing _Float128 (without inline functions)
UBSAN: Undefined behaviour in ../sysdeps/ieee754/float128/../ldbl-128/s_llroundl.c:65:37 left shift of 562949953421312 by 14 cannot be represented in type 'long long int'
Aborted
---

diff --git a/sysdeps/ieee754/ldbl-128/s_llroundl.c b/sysdeps/ieee754/ldbl-128/s_llroundl.c
index 752b097944..aef602e2f5 100644
--- a/sysdeps/ieee754/ldbl-128/s_llroundl.c
+++ b/sysdeps/ieee754/ldbl-128/s_llroundl.c
@@ -62,7 +62,7 @@ __llroundl (_Float128 x)
 	    result = (long long int) i0;
 	  else
 	    {
-	      result = ((long long int) i0 << (j0 - 48)) | (j >> (112 - j0));
+	      result = (i0 << (j0 - 48)) | (j >> (112 - j0));
 #ifdef FE_INVALID
 	      if (sign == 1 && result == LLONG_MIN)
 		/* Rounding brought the value out of range.  */