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crash in del_inactive_lemmas2 #19

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nunoplopes opened this issue Mar 31, 2015 · 1 comment
Closed

crash in del_inactive_lemmas2 #19

nunoplopes opened this issue Mar 31, 2015 · 1 comment

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@nunoplopes
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The following code crashes Z3:

from z3 import *

cond = BitVec('cond', 1)
p = BitVec('p', 32)
mem0 = Array('mem0', BitVecSort(32), BitVecSort(8))

fml = And(If(cond == 1, 0, p) != 0,
          mem0[If(cond == 1, 0, p) + 1] != mem0[p + 1])

s = Solver()
s.add(fml)
print s.check()

Trace:

#0  0x00aae767 in smt::context::del_inactive_lemmas2 (this=0x801f7534)
    at ../src/smt/smt_context.cpp:2636
#1  0x00ab6835 in del_inactive_lemmas (this=0x801f7534)
    at ../src/smt/smt_context.cpp:2538
#2  smt::context::bounded_search (this=this@entry=0x801f7534)
    at ../src/smt/smt_context.cpp:3317
#3  0x00ab691a in smt::context::search (this=this@entry=0x801f7534)
    at ../src/smt/smt_context.cpp:3180
#4  0x00ab6ec8 in smt::context::setup_and_check (this=0x801f7534,
    reset_cancel=reset_cancel@entry=true) at ../src/smt/smt_context.cpp:2985
#5  0x00aca699 in setup_and_check (this=<optimized out>)
    at ../src/smt/smt_kernel.cpp:87
#6  smt::kernel::setup_and_check (this=this@entry=0x8018254c)
    at ../src/smt/smt_kernel.cpp:249
#7  0x00e4009f in smt_tactic::operator() (this=0x8023c324, in=..., result=...,
    mc=..., pc=..., core=...) at ../src/smt/tactic/smt_tactic.cpp:220
#8  0x00fee5c4 in and_then_tactical::operator() (this=0x8023c62c, in=...,
    result=..., mc=..., pc=..., core=...) at ../src/tactic/tactical.cpp:167
#9  0x00fee5c4 in and_then_tactical::operator() (this=0x80242e7c, in=...,
    result=..., mc=..., pc=..., core=...) at ../src/tactic/tactical.cpp:167
#10 0x00c691a5 in exec (t=..., in=..., result=..., mc=..., pc=..., core=...)
    at ../src/tactic/tactic.cpp:179
#11 0x00c69632 in check_sat (t=..., g=..., md=..., pr=..., core=...,
    reason_unknown=...) at ../src/tactic/tactic.cpp:201
@nunoplopes
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false alarm, sorry.
I mixed gcc and MSVC binaries.

@itszor itszor mentioned this issue Jun 1, 2015
Closed
NikolajBjorner pushed a commit to NikolajBjorner/z3 that referenced this issue Jul 10, 2016
@levnach
Merge pull request Z3Prover#19 from NikolajBjorner/lev
4fdce45 
refine handling of underspecified operators, add statistics for numbe…
@qingkaishi qingkaishi mentioned this issue Nov 21, 2016
Closed
This was referenced Jan 31, 2018
Closed
Closed
@levnach levnach mentioned this issue Nov 28, 2018
Closed
@evmaus evmaus mentioned this issue May 24, 2019
Closed
@levnach levnach mentioned this issue Mar 3, 2020
Closed
@5hadowblad3 5hadowblad3 mentioned this issue Mar 16, 2020
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@levnach levnach mentioned this issue Mar 18, 2020
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@rainoftime rainoftime mentioned this issue Apr 6, 2020
Closed
mtzguido added a commit to mtzguido/z3 that referenced this issue Jun 23, 2023
@mtzguido
bool_rewriter: fix possible segfault when disabling rewriter.sort_dis…
ccd828e 
…junctions

After introducing the rewriter.sort_disjunctions option, I noticed a
segfault in a Z3 run that was working fine for me.

I traced the difference to a slight discrepancy between the first patch
I submitted and the one we ended up merging: my first version would skip
sorting the disjuncts in mk_nflat_core, but still return BR_DONE, while
the patch in master returns BR_FAILED instead.

This patch fixes the problem for me, and it makes slightly more sense
to me to return a BR_DONE since, if `s` is true, some disjunct (e.g. a
`false` or a repeat) might have been simplified away. However I don't
fully understand this code.

.. and I can't say I understand why the segfault happens. Perhaps that
is a separate issue?

This is the file to reproduce:
 https://gist.github.com/mtzguido/b7360c74d3d2e42d89f1bd9149ad26f6

Here's a stack trace of the failure, mk_nflat_or_core is not involved.
```
 (gdb) where
 #0  0x0000555555b98497 in smt::context::get_lit_assignment(unsigned int) const ()
 Z3Prover#1  0x0000555555b984cb in smt::context::get_assignment(sat::literal) const ()
 Z3Prover#2  0x0000555555b98504 in smt::context::get_assignment(unsigned int) const ()
 Z3Prover#3  0x0000555555ca83b8 in smt::context::get_assignment_core(expr*) const ()
 Z3Prover#4  0x0000555555c9af5a in smt::context::get_assignment(expr*) const ()
 Z3Prover#5  0x0000555555d7bd1d in (anonymous namespace)::has_child_assigned_to(smt::context&, app*, lbool, expr*&, unsigned int) ()
 Z3Prover#6  0x0000555555d7c413 in (anonymous namespace)::rel_case_split_queue::next_case_split_core(ptr_vector<expr>&, unsigned int&, unsigned int&, lbool&) ()
 Z3Prover#7  0x0000555555d7c589 in (anonymous namespace)::rel_case_split_queue::next_case_split(unsigned int&, lbool&) ()
 Z3Prover#8  0x0000555555c9c1b7 in smt::context::decide() ()
 Z3Prover#9  0x0000555555ca39fd in smt::context::bounded_search() ()
 Z3Prover#10 0x0000555555ca30c2 in smt::context::search() ()
 Z3Prover#11 0x0000555555ca273d in smt::context::check(unsigned int, expr* const*, bool) ()
 Z3Prover#12 0x0000555555cb166a in smt::kernel::check(unsigned int, expr* const*) ()
 Z3Prover#13 0x0000555555cb9695 in (anonymous namespace)::smt_solver::check_sat_core2(unsigned int, expr* const*) ()
 Z3Prover#14 0x00005555560dc0c6 in solver_na2as::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#15 0x00005555560d73f3 in combined_solver::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#16 0x00005555560d34e3 in solver::check_sat(unsigned int, expr* const*) ()
 Z3Prover#17 0x0000555556097b26 in cmd_context::check_sat(unsigned int, expr* const*) ()
 Z3Prover#18 0x0000555556082ff0 in smt2::parser::parse_check_sat() ()
 Z3Prover#19 0x0000555556084dc0 in smt2::parser::parse_cmd() ()
 Z3Prover#20 0x00005555560861b6 in smt2::parser::operator()() ()
 Z3Prover#21 0x00005555560757e6 in parse_smt2_commands(cmd_context&, std::basic_istream<char, std::char_traits<char> >&, bool, params_ref const&, char const*) ()
 Z3Prover#22 0x00005555555e8f68 in read_smtlib2_commands(char const*) ()
 Z3Prover#23 0x00005555555ee6f6 in main ()
 (gdb)
```
mtzguido added a commit to mtzguido/z3 that referenced this issue Jun 23, 2023
@mtzguido
bool_rewriter: fix possible segfault when disabling rewriter.sort_dis…
c9c5f1e 
…junctions

After introducing the rewriter.sort_disjunctions option (Z3Prover#6774), I
noticed a segfault in a Z3 run that was working fine for me before the
PR.

I traced the difference to a slight discrepancy between the first patch
I submitted and the one we ended up merging: my first version would skip
sorting the disjuncts in mk_nflat_core, but still return BR_DONE, while
the patch in master returns BR_FAILED instead.

This patch fixes that problem, and it makes slightly more sense to me to
return a BR_DONE since, if `s` is true, some disjunct (e.g. a `false`
or a repeat) might have been simplified away. However I don't fully
understand this code.

... and I can't say I understand why the segfault happens. Perhaps that
is a separate issue?

This is the file to reproduce:
 https://gist.github.com/mtzguido/b7360c74d3d2e42d89f1bd9149ad26f6

Here's a stack trace of the failure, mk_nflat_or_core is not involved.
```
 (gdb) where
 #0  0x0000555555b98497 in smt::context::get_lit_assignment(unsigned int) const ()
 Z3Prover#1  0x0000555555b984cb in smt::context::get_assignment(sat::literal) const ()
 Z3Prover#2  0x0000555555b98504 in smt::context::get_assignment(unsigned int) const ()
 Z3Prover#3  0x0000555555ca83b8 in smt::context::get_assignment_core(expr*) const ()
 Z3Prover#4  0x0000555555c9af5a in smt::context::get_assignment(expr*) const ()
 Z3Prover#5  0x0000555555d7bd1d in (anonymous namespace)::has_child_assigned_to(smt::context&, app*, lbool, expr*&, unsigned int) ()
 Z3Prover#6  0x0000555555d7c413 in (anonymous namespace)::rel_case_split_queue::next_case_split_core(ptr_vector<expr>&, unsigned int&, unsigned int&, lbool&) ()
 Z3Prover#7  0x0000555555d7c589 in (anonymous namespace)::rel_case_split_queue::next_case_split(unsigned int&, lbool&) ()
 Z3Prover#8  0x0000555555c9c1b7 in smt::context::decide() ()
 Z3Prover#9  0x0000555555ca39fd in smt::context::bounded_search() ()
 Z3Prover#10 0x0000555555ca30c2 in smt::context::search() ()
 Z3Prover#11 0x0000555555ca273d in smt::context::check(unsigned int, expr* const*, bool) ()
 Z3Prover#12 0x0000555555cb166a in smt::kernel::check(unsigned int, expr* const*) ()
 Z3Prover#13 0x0000555555cb9695 in (anonymous namespace)::smt_solver::check_sat_core2(unsigned int, expr* const*) ()
 Z3Prover#14 0x00005555560dc0c6 in solver_na2as::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#15 0x00005555560d73f3 in combined_solver::check_sat_core(unsigned int, expr* const*) ()
 Z3Prover#16 0x00005555560d34e3 in solver::check_sat(unsigned int, expr* const*) ()
 Z3Prover#17 0x0000555556097b26 in cmd_context::check_sat(unsigned int, expr* const*) ()
 Z3Prover#18 0x0000555556082ff0 in smt2::parser::parse_check_sat() ()
 Z3Prover#19 0x0000555556084dc0 in smt2::parser::parse_cmd() ()
 Z3Prover#20 0x00005555560861b6 in smt2::parser::operator()() ()
 Z3Prover#21 0x00005555560757e6 in parse_smt2_commands(cmd_context&, std::basic_istream<char, std::char_traits<char> >&, bool, params_ref const&, char const*) ()
 Z3Prover#22 0x00005555555e8f68 in read_smtlib2_commands(char const*) ()
 Z3Prover#23 0x00005555555ee6f6 in main ()
 (gdb)
```
NikolajBjorner pushed a commit that referenced this issue Jun 23, 2023
@mtzguido
bool_rewriter: fix possible segfault when disabling rewriter.sort_dis…
7c380fd 
…junctions (#6779)

After introducing the rewriter.sort_disjunctions option (#6774), I
noticed a segfault in a Z3 run that was working fine for me before the
PR.

I traced the difference to a slight discrepancy between the first patch
I submitted and the one we ended up merging: my first version would skip
sorting the disjuncts in mk_nflat_core, but still return BR_DONE, while
the patch in master returns BR_FAILED instead.

This patch fixes that problem, and it makes slightly more sense to me to
return a BR_DONE since, if `s` is true, some disjunct (e.g. a `false`
or a repeat) might have been simplified away. However I don't fully
understand this code.

... and I can't say I understand why the segfault happens. Perhaps that
is a separate issue?

This is the file to reproduce:
 https://gist.github.com/mtzguido/b7360c74d3d2e42d89f1bd9149ad26f6

Here's a stack trace of the failure, mk_nflat_or_core is not involved.
```
 (gdb) where
 #0  0x0000555555b98497 in smt::context::get_lit_assignment(unsigned int) const ()
 #1  0x0000555555b984cb in smt::context::get_assignment(sat::literal) const ()
 #2  0x0000555555b98504 in smt::context::get_assignment(unsigned int) const ()
 #3  0x0000555555ca83b8 in smt::context::get_assignment_core(expr*) const ()
 #4  0x0000555555c9af5a in smt::context::get_assignment(expr*) const ()
 #5  0x0000555555d7bd1d in (anonymous namespace)::has_child_assigned_to(smt::context&, app*, lbool, expr*&, unsigned int) ()
 #6  0x0000555555d7c413 in (anonymous namespace)::rel_case_split_queue::next_case_split_core(ptr_vector<expr>&, unsigned int&, unsigned int&, lbool&) ()
 #7  0x0000555555d7c589 in (anonymous namespace)::rel_case_split_queue::next_case_split(unsigned int&, lbool&) ()
 #8  0x0000555555c9c1b7 in smt::context::decide() ()
 #9  0x0000555555ca39fd in smt::context::bounded_search() ()
 #10 0x0000555555ca30c2 in smt::context::search() ()
 #11 0x0000555555ca273d in smt::context::check(unsigned int, expr* const*, bool) ()
 #12 0x0000555555cb166a in smt::kernel::check(unsigned int, expr* const*) ()
 #13 0x0000555555cb9695 in (anonymous namespace)::smt_solver::check_sat_core2(unsigned int, expr* const*) ()
 #14 0x00005555560dc0c6 in solver_na2as::check_sat_core(unsigned int, expr* const*) ()
 #15 0x00005555560d73f3 in combined_solver::check_sat_core(unsigned int, expr* const*) ()
 #16 0x00005555560d34e3 in solver::check_sat(unsigned int, expr* const*) ()
 #17 0x0000555556097b26 in cmd_context::check_sat(unsigned int, expr* const*) ()
 #18 0x0000555556082ff0 in smt2::parser::parse_check_sat() ()
 #19 0x0000555556084dc0 in smt2::parser::parse_cmd() ()
 #20 0x00005555560861b6 in smt2::parser::operator()() ()
 #21 0x00005555560757e6 in parse_smt2_commands(cmd_context&, std::basic_istream<char, std::char_traits<char> >&, bool, params_ref const&, char const*) ()
 #22 0x00005555555e8f68 in read_smtlib2_commands(char const*) ()
 #23 0x00005555555ee6f6 in main ()
 (gdb)
```
@rammohan02 rammohan02 mentioned this issue Feb 10, 2024
Closed
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@nunoplopes