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9333498794
Bug 25487 reports stack corruption in ldbl-96 sinl on a pseudo-zero argument (an representation where all the significand bits, including the explicit high bit, are zero, but the exponent is not zero, which is not a valid representation for the long double type). Although this is not a valid long double representation, existing practice in this area (see bug 4586, originally marked invalid but subsequently fixed) is that we still seek to avoid invalid memory accesses as a result, in case of programs that treat arbitrary binary data as long double representations, although the invalid representations of the ldbl-96 format do not need to be consistently handled the same as any particular valid representation. This patch makes the range reduction detect pseudo-zero and unnormal representations that would otherwise go to __kernel_rem_pio2, and returns a NaN for them instead of continuing with the range reduction process. (Pseudo-zero and unnormal representations whose unbiased exponent is less than -1 have already been safely returned from the function before this point without going through the rest of range reduction.) Pseudo-zero representations would previously result in the value passed to __kernel_rem_pio2 being all-zero, which is definitely unsafe; unnormal representations would previously result in a value passed whose high bit is zero, which might well be unsafe since that is not a form of input expected by __kernel_rem_pio2. Tested for x86_64.
42 lines
1.3 KiB
C
42 lines
1.3 KiB
C
/* Test sinl for pseudo-zeros and unnormals for ldbl-96 (bug 25487).
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <math.h>
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#include <math_ldbl.h>
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#include <stdint.h>
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static int
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do_test (void)
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{
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for (int i = 0; i < 64; i++)
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{
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uint64_t sig = i == 63 ? 0 : 1ULL << i;
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long double ld;
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SET_LDOUBLE_WORDS (ld, 0x4141,
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sig >> 32, sig & 0xffffffffULL);
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/* The requirement is that no stack overflow occurs when the
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pseudo-zero or unnormal goes through range reduction. */
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volatile long double ldr;
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ldr = sinl (ld);
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(void) ldr;
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}
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return 0;
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}
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#include <support/test-driver.c>
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