From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Mon, 5 May 2025 13:48:40 +0000 (-0300)
Subject: math: Fix UB in ldbl-128 powl
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8175ef182f0645a91be6035d245727b797776c59;p=thirdparty%2Fglibc.git

math: Fix UB in ldbl-128 powl

testing _Float128 (without inline functions)
UBSAN: Undefined behaviour in ../sysdeps/ieee754/float128/../ldbl-128/e_powl.c:439:11 left shift of 4294953849 by 16 cannot be represented in type 'int'
---

diff --git a/sysdeps/ieee754/ldbl-128/e_powl.c b/sysdeps/ieee754/ldbl-128/e_powl.c
index 4e20616705..cec2e9990b 100644
--- a/sysdeps/ieee754/ldbl-128/e_powl.c
+++ b/sysdeps/ieee754/ldbl-128/e_powl.c
@@ -436,7 +436,7 @@ __ieee754_powl (_Float128 x, _Float128 y)
   z = one - (r - z);
   o.value = z;
   j = o.parts32.w0;
-  j += (n << 16);
+  j += ((uint32_t)n << 16);
   if ((j >> 16) <= 0)
     {
       z = __scalbnl (z, n);	/* subnormal output */