From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Fri, 25 Apr 2025 20:54:24 +0000 (-0300)
Subject: math: Fix UB on logf (BZ 32920)
X-Git-Tag: glibc-2.42~279
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=de0c4adf94a379873c0167f792519e91df28c3ed;p=thirdparty%2Fglibc.git

math: Fix UB on logf (BZ 32920)

The left shift overflows for 'int', use a literal instead.  It syncs
with OPTIMIZED-ROUTINES commit 0f87f607b976820ef41fe64d004fe67dc7af8236.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
---

diff --git a/sysdeps/ieee754/flt-32/e_logf.c b/sysdeps/ieee754/flt-32/e_logf.c
index 6a595cf7f0..207151c76a 100644
--- a/sysdeps/ieee754/flt-32/e_logf.c
+++ b/sysdeps/ieee754/flt-32/e_logf.c
@@ -70,7 +70,7 @@ __logf (float x)
   tmp = ix - OFF;
   i = (tmp >> (23 - LOGF_TABLE_BITS)) % N;
   k = (int32_t) tmp >> 23; /* arithmetic shift */
-  iz = ix - (tmp & 0x1ff << 23);
+  iz = ix - (tmp & 0xff800000);
   invc = T[i].invc;
   logc = T[i].logc;
   z = (double_t) asfloat (iz);