| Summary: | log2(0) and log10(0) are wrong in downward rounding without the svid compat wrapper | ||
|---|---|---|---|
| Product: | glibc | Reporter: | Szabolcs Nagy <nszabolcs> |
| Component: | math | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | Flags: | fweimer:
security-
|
| Priority: | P2 | ||
| Version: | 2.27 | ||
| Target Milestone: | 2.27 | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | ||
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- Log -----------------------------------------------------------------
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=86c27ade1e44e29922d33676f950f7334edb37a7
commit 86c27ade1e44e29922d33676f950f7334edb37a7
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Tue Oct 3 18:12:42 2017 +0100
[BZ #22244] Fix yn(n,0) without SVID wrapper
Without SVID compat wrapper yn(n,0) and ynf(n,0) does not raise
the divide-by-zero excpetion and it may return inf with the wrong
sign for n < 0.
[BZ #22244]
* sysdeps/ieee754/dbl-64/e_jn.c (__ieee754_yn): Fix x == 0 case.
* sysdeps/ieee754/flt-32/e_jnf.c (__ieee754_ynf): Likewise.
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=8f8f8ef7aba40ef883291e4c4d95a419c3327d70
commit 8f8f8ef7aba40ef883291e4c4d95a419c3327d70
Author: Szabolcs Nagy <szabolcs.nagy@arm.com>
Date: Tue Oct 3 17:13:18 2017 +0100
[BZ #22243] fix log2(0) and log(10) in downward rounding
On 64bit targets if the SVID compat wrapper is suppressed (e.g. static linking)
then log2(0) and log10(0) returned inf instead of -inf.
[BZ #22243]
* sysdeps/ieee754/dbl-64/wordsize-64/e_log10.c (__ieee754_log10): Use fabs.
* sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c (__ieee754_log2): Likewise.
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 12 ++++++++++++
sysdeps/ieee754/dbl-64/e_jn.c | 10 +++++-----
sysdeps/ieee754/dbl-64/wordsize-64/e_log10.c | 2 +-
sysdeps/ieee754/dbl-64/wordsize-64/e_log2.c | 2 +-
sysdeps/ieee754/flt-32/e_jnf.c | 6 +++---
5 files changed, 22 insertions(+), 10 deletions(-)
fixed. |
log2(0) and log10(0) return inf instead of -inf in downward rounding when the svid wrapper is suppressed (static linking, new targets). #include <math.h> #include <stdio.h> #include <fenv.h> int main() { fesetround(FE_DOWNWARD); double y1 = log2(0); double y2 = log10(0); fesetround(FE_TONEAREST); printf("%a\n", y1); printf("%a\n", y2); } prints inf inf with static linking.