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| author |   Aurelien Jarno <aurelien@aurel32.net> | 2022-10-10 00:39:33 +0200 |
|---|---|---|
| committer |   Andreas K. Hüttel <dilfridge@gentoo.org> | 2022-11-12 22:10:15 +0100 |
| commit | ab60bdaa80c9a67a40e311f3063fba3a5c49aded (patch) | |
| tree | daf3b4bccf7d292a41e24f384960d5637dfb9f59 | |
| parent | Fix BZ #29463 in the ibm128 implementation of y1l too (diff) | |
| download | glibc-ab60bdaa80c9a67a40e311f3063fba3a5c49aded.tar.gz glibc-ab60bdaa80c9a67a40e311f3063fba3a5c49aded.tar.bz2 glibc-ab60bdaa80c9a67a40e311f3063fba3a5c49aded.zip | |
Avoid undefined behaviour in ibm128 implementation of llroundl (BZ #29488)
Detecting an overflow edge case depended on signed overflow of a long
long. Replace the additions and the overflow checks by
__builtin_add_overflow().
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
(cherry picked from commit 2b5478569e72ee4820a6e163d306690c9c0eaf5e)
(cherry picked from commit 9273b2d0e93e7355656cad3be3a1ca76489df483)
Signed-off-by: Andreas K. Hüttel <dilfridge@gentoo.org>
| -rw-r--r-- | NEWS | 2 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/s_llroundl.c | 21 |
2 files changed, 11 insertions, 12 deletions
@@ -33,6 +33,8 @@ The following bugs are resolved with this release: [29485] Linux: Terminate subprocess on late failure in tst-pidfd [29490] alpha: New __brk_call implementation is broken [29463] math/test-float128-y1 fails on x86_64 + [29488] test-ibm128-llround fails on ppc64el when built with gcc-12 and -O2 + or higher [29528] elf: Call __libc_early_init for reused namespaces [29537] libc: [2.34 regression]: Alignment issue on m68k when using [29539] libc: LD_TRACE_LOADED_OBJECTS changed how vDSO library are diff --git a/sysdeps/ieee754/ldbl-128ibm/s_llroundl.c b/sysdeps/ieee754/ldbl-128ibm/s_llroundl.c index d85154e73a..d8c0de1faf 100644 --- a/sysdeps/ieee754/ldbl-128ibm/s_llroundl.c +++ b/sysdeps/ieee754/ldbl-128ibm/s_llroundl.c @@ -66,38 +66,35 @@ __llroundl (long double x) /* Peg at max/min values, assuming that the above conversions do so. Strictly speaking, we can return anything for values that overflow, but this is more useful. */ - res = hi + lo; - - /* This is just sign(hi) == sign(lo) && sign(res) != sign(hi). */ - if (__glibc_unlikely (((~(hi ^ lo) & (res ^ hi)) < 0))) + if (__glibc_unlikely (__builtin_add_overflow (hi, lo, &res))) goto overflow; xh -= lo; ldbl_canonicalize (&xh, &xl); - hi = res; if (xh > 0.5) { - res += 1; + if (__glibc_unlikely (__builtin_add_overflow (res, 1, &res))) + goto overflow; } else if (xh == 0.5) { if (xl > 0.0 || (xl == 0.0 && res >= 0)) - res += 1; + if (__glibc_unlikely (__builtin_add_overflow (res, 1, &res))) + goto overflow; } else if (-xh > 0.5) { - res -= 1; + if (__glibc_unlikely (__builtin_add_overflow (res, -1, &res))) + goto overflow; } else if (-xh == 0.5) { if (xl < 0.0 || (xl == 0.0 && res <= 0)) - res -= 1; + if (__glibc_unlikely (__builtin_add_overflow (res, -1, &res))) + goto overflow; } - if (__glibc_unlikely (((~(hi ^ (res - hi)) & (res ^ hi)) < 0))) - goto overflow; - return res; } else |