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authorBernd Edlinger <bernd.edlinger@hotmail.de>2017-12-19 18:41:01 +0000
committerJoseph Myers <joseph@codesourcery.com>2017-12-19 18:41:01 +0000
commit648615e13f8d7b638cb911926b8bb70804217f15 (patch)
treef2c1e2e3d031d0f4e72b982950ee5a6b9223e5a9
parentf1e005022ebd246e1541386cd2f3286f008d2d98 (diff)
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Avoid signed shift overflow in pow (bug 21309).
As noted in bug 21309, dbl-64/e_pow.c contains signed int shifts that, although the shift count is in the range [0, 31], shift bits into and beyond the sign bit and so are undefined in ISO C. Although this is defined in GNU C, this patch from the bug cleans up the code to avoid those shifts. Tested for x86_64. [BZ #21309] * sysdeps/ieee754/dbl-64/e_pow.c (checkint): Make m and n unsigned.
-rw-r--r--ChangeLog6
-rw-r--r--sysdeps/ieee754/dbl-64/e_pow.c3
2 files changed, 8 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index 4f836e3f67..d194a73592 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-12-19 Bernd Edlinger <bernd.edlinger@hotmail.de>
+
+ [BZ #21309]
+ * sysdeps/ieee754/dbl-64/e_pow.c (checkint): Make m and n
+ unsigned.
+
2017-12-19 Joseph Myers <joseph@codesourcery.com>
Revert:
diff --git a/sysdeps/ieee754/dbl-64/e_pow.c b/sysdeps/ieee754/dbl-64/e_pow.c
index 9f6439ee42..8c7fb74549 100644
--- a/sysdeps/ieee754/dbl-64/e_pow.c
+++ b/sysdeps/ieee754/dbl-64/e_pow.c
@@ -452,7 +452,8 @@ checkint (double x)
int4 i[2];
double x;
} u;
- int k, m, n;
+ int k;
+ unsigned int m, n;
u.x = x;
m = u.i[HIGH_HALF] & 0x7fffffff; /* no sign */
if (m >= 0x7ff00000)