On 11/27/2014 03:20 PM, Paul wrote:
Here is how it looks with debug symbols are on:
#0 0x28c4113e in memcpy () from /lib/libc.so.7
#1 0x08854c20 in sqlite3StrAccumAppend (p=0xfffe8548, z=0x2c3fffda "vtb_enyqkyxs
USING vtable_module_343", N=41) at sqlite3.c:21563
#2 0x087edf30 in sqlite3VXPrintf (pAccum=0xfffe8548, bFlags=1, fmt=0x892e543 "T",
ap=0xfffe8610 "") at sqlite3.c:21439
#3 0x088077d5 in sqlite3VMPrintf (db=0x2c006788, zFormat=0x892e52d "CREATE VIRTUAL TABLE
%T", ap=0xfffe860c "xx") at sqlite3.c:21638
#4 0x087f815e in sqlite3MPrintf (db=0x2c006788, zFormat=0x892e52d "CREATE VIRTUAL
TABLE %T") at sqlite3.c:21654
#5 0x088759af in sqlite3VtabFinishParse (pParse=0x2c007688, pEnd=0x0) at
sqlite3.c:112383
#6 0x0885bb21 in yy_reduce (yypParser=0x2c1d1408, yyruleno=309) at
sqlite3.c:123403
#7 0x08856180 in sqlite3Parser (yyp=0x2c1d1408, yymajor=1, yyminor=...,
pParse=0x2c007688) at sqlite3.c:123629
#8 0x087fc289 in sqlite3RunParser (pParse=0x2c007688, zSql=0x2c3fffc0 "CREATE
VIRTUAL TABLE temp.vtb_enyqkyxs USING vtable_module_343", pzErrMsg=0xfffe8bc4) at
sqlite3.c:124466
#9 0x088bbc82 in sqlite3Prepare (db=0x2c006788, zSql=0x2c3fffc0 "CREATE VIRTUAL
TABLE temp.vtb_enyqkyxs USING vtable_module_343", nBytes=-1, saveSqlFlag=1,
pReprepare=0x0, ppStmt=0xfffe8d0c, pzTail=0xfffe8d10) at sqlite3.c:103750
#10 0x087fb0ce in sqlite3LockAndPrepare (db=0x2c006788, zSql=0x2c3fffc0 "CREATE
VIRTUAL TABLE temp.vtb_enyqkyxs USING vtable_module_343", nBytes=-1, saveSqlFlag=1,
pOld=0x0, ppStmt=0xfffe8d0c, pzTail=0xfffe8d10) at sqlite3.c:103842
#11 0x087fa504 in sqlite3_prepare_v2 (db=0x2c006788, zSql=0x2c3fffc0 "CREATE VIRTUAL
TABLE temp.vtb_enyqkyxs USING vtable_module_343", nBytes=-1, ppStmt=0xfffe8d0c,
pzTail=0xfffe8d10) at sqlite3.c:103918
#12 0x087fa01d in sqlite3_exec (db=0x2c006788, zSql=0x2c3fffc0 "CREATE VIRTUAL TABLE
temp.vtb_enyqkyxs USING vtable_module_343", xCallback=0x0, pArg=0x0, pzErrMsg=0x0)
at sqlite3.c:99345
#13 0x086588e7 in sqlite::StorageBase::exec_query (this=0x2c3ff640, query=0x2c3fffc0
"CREATE VIRTUAL TABLE temp.vtb_enyqkyxs USING vtable_module_343", quiet=false)
at SqliteStorageBase.cpp:286
Interesting part is in frame #5
#5 0x088759af in sqlite3VtabFinishParse (pParse=0x2c007688, pEnd=0x0) at
sqlite3.c:112383
112383 zStmt = sqlite3MPrintf(db, "CREATE VIRTUAL TABLE %T",
&pParse->sNameToken);
(gdb) p pParse->sNameToken
$12 = {
z = 0x2c3fffda "vtb_enyqkyxs USING vtable_module_343",
n = 41
}
(gdb) p pParse->sNameToken.z + 40
$13 = 0x2c400002 <error: Cannot access memory at address 0x2c400002>
As you can see, token size is invalid: 41. This causes memcpy() down at #0 to
access invalid, unmapped address.
Hopefully it is only read overflow so the only consequence is just an
occasional Segmentation fault when allocated
piece of string is at the specific place: near the end of the page in front of
unmapped page.
Should I fill a bug report?
It's certainly very suspicious. Which SQLite version are you using?
Dan.
Is there a way to work this around?
Like append many spaces a the end of query?
Or maybe the problem is in absence of ';' at the end of query?
Meantime I'll try both of these cases.
We observe very similar problem.
#1 0x087ec9f7 in sqlite3VXPrintf ()
#2 0x087f816d in sqlite3MPrintf ()
#3 0x088781e5 in sqlite3VtabFinishParse ()
#4 0x0885190f in yy_reduce ()
#5 0x0884d4d8 in sqlite3Parser ()
#6 0x087fc0ce in sqlite3RunParser ()
#7 0x088aa396 in sqlite3Prepare ()
#8 0x087fae18 in sqlite3LockAndPrepare ()
#9 0x087f9a88 in sqlite3_exec ()
#10 0x086588a7 in sqlite::StorageBase::exec_query (this=0x2c2a47c0, query=0x2c7fffc0
"CREATE VIRTUAL TABLE temp.vtb_wayxzmbo USING vtable_module_344", quiet=false)
at SqliteStorageBase.cpp:286
It always crashes when "CREATE VIRTUAL TABLE ..." is being executed, always
with the same backtrace.
I spent many days reviewing and testing my code to eliminate possible cause but
so far I see nothing wrong with it.
Probability of this crash is so very low so that problem can be reproduced only
on hi loaded production servers.
(Where such virtual tables are created and dropped millions of times during a
day)
I am going to compile sqlite without optimizations and with debug symbols and
wait for a crash
to try and track the root of the problem from within sqlite.
Though I doubt very much this is sqlite problem at all and not an incorrect
vtable implementation on my side.
SQLite version 3.8.6 2014-08-15 11:46:33
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
