Opened 9 years ago

Last modified 7 years ago

#12480 closed defect

NTL segfault on OS X 10.7 — at Version 2

Reported by: jdemeyer Owned by: was
Priority: critical Milestone: sage-5.0
Component: interfaces Keywords:
Cc: Merged in:
Authors: Reviewers:
Report Upstream: N/A Work issues:
Branch: Commit:
Dependencies: Stopgaps:

Status badges

Description (last modified by jdemeyer)

On OS X 10.7 (compiled with gcc-4.6.2, #12369), executing the following code:

R = Zp(5,5)
S.<x> = R[]
f = x^5 + 75*x^3 - 15*x^2 +125*x - 5
W.<w> = R.ext(f)
pol = ntl.ZZ_pX([5^40,5^42,3*5^41], 5^44)
W(pol, relprec = 0)

crashes Sage:

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000300000002
0x0000000101791ae1 in CopyPointer (dst=@0x10190b700, src=0x300000002) at ZZ_p.c:157
157           if (src->ref_count == NTL_MAX_LONG)
Current language:  auto; currently c++
(gdb) bt
#0  0x0000000101791ae1 in CopyPointer (dst=@0x10190b700, src=0x300000002) at ZZ_p.c:157
#1  0x0000000101791d46 in NTL::ZZ_pContext::restore (this=0x100191148) at ZZ_p.c:205
#2  0x000000010164e1aa in ZZ_pX_conv_modulus ()
#3  0x00000001063a1ff7 in __pyx_f_4sage_5rings_6padics_16pow_computer_ext_ZZ_pX_eis_shift_p (__pyx_v_self=0x10db203f0, __pyx_v_x=0x10e057f18, __pyx_v_a=0x10e057f18, __pyx_v_n=200, __pyx_v_finalprec=0) at pow_computer_ext.cpp:6173
#4  0x0000000106392871 in __pyx_f_4sage_5rings_6padics_16pow_computer_ext_27PowComputer_ZZ_pX_small_Eis_eis_shift (__pyx_v_self=0x10db203f0, __pyx_v_x=0x10e057f18, __pyx_v_a=0x10e057f18, __pyx_v_n=200, __pyx_v_finalprec=0) at pow_computer_ext.cpp:12917
#5  0x000000010638aced in __pyx_f_4sage_5rings_6padics_16pow_computer_ext_17PowComputer_ZZ_pX_eis_shift_capdiv (__pyx_v_self=0x10db203f0, __pyx_v_x=0x10e057f18, __pyx_v_a=0x10e057f18, __pyx_v_n=200, __pyx_v_finalprec=0) at pow_computer_ext.cpp:9448
#6  0x00000001064e0aba in __pyx_f_4sage_5rings_6padics_22padic_ZZ_pX_CR_element_18pAdicZZpXCRElement__internal_lshift (__pyx_v_self=0x10e057ef0, __pyx_v_shift=-200) at padic_ZZ_pX_CR_element.cpp:9197
#7  0x00000001064dfd8b in __pyx_f_4sage_5rings_6padics_22padic_ZZ_pX_CR_element_18pAdicZZpXCRElement__set_from_ZZ_pX_part2 (__pyx_v_self=0x10e057ef0, __pyx_v_poly=0x10e075f98) at padic_ZZ_pX_CR_element.cpp:8445
#8  0x00000001064de4c7 in __pyx_f_4sage_5rings_6padics_22padic_ZZ_pX_CR_element_18pAdicZZpXCRElement__set_from_ZZ_pX_rel (__pyx_v_self=0x10e057ef0, __pyx_v_poly=0x10e075f98, __pyx_v_ctx=0x10e078730, __pyx_v_relprec=0) at padic_ZZ_pX_CR_element.cpp:8146
#9  0x00000001064fe4ee in __pyx_pf_4sage_5rings_6padics_22padic_ZZ_pX_CR_element_18pAdicZZpXCRElement___init__ (__pyx_v_self=0x10e057ef0, __pyx_args=0x10db23d40, __pyx_kwds=0x10da8f290) at padic_ZZ_pX_CR_element.cpp:5163
#10 0x000000010007a1a7 in type_call ()
Previous frame inner to this frame (gdb could not unwind past this frame)

This is a huge can of worms. In sage/rings/padics/pow_computer_ext.pyx:

    cdef ntl_ZZ_pContext_class get_context(self, long n):
        """
        Returns the context for p^n.

        Note that this function will raise an Index error if n > self.cache_limit.
        Also, it will return None on input 0

On input 0, we have a Py_None typecast to a ntl_ZZ_pContext_class. How does this make sense? The fact that it crashes on OS X 10.7 is expected, the surprising thing is that this doesn't crash on other systems.

Change History (2)

comment:1 Changed 9 years ago by jdemeyer

  • Description modified (diff)

comment:2 Changed 9 years ago by jdemeyer

  • Description modified (diff)
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