Hi,
I have a database with 10million of row in one table (file size is ~5GB)
When I execute a query that should return half of this table, sqlite fails
because at some point there is no memory (this is normal) but instead of
returning an error, it crashes.
sqlite version: 3.7.5
#0 0x000000000065b70e in sqlite3_get_table (db=0x7fffe0023d08,
zSql=0x7fffc001a6e8 "SELECT * FROM sync_snapdb_table WHERE tobe_deleted
= 0 AND scn_not_visited < 30 AND 1 =
callback_cache_filter_check(record_id);",
pazResult=0x7fffdabfa110, pnRow=0x7fffdabfa16c, pnColumn=0x7fffdabfa168,
pzErrMsg=0x7fffdabfa118)
at /mytest/imports/3rdparty/sqlite/sqlite3.c:92643
After some investigation, i found that sqlite3_get_table_cb is called with
nAlloc equals to ~164856293, a realloc is requested and nAlloc is now ~325
000 000
So sqlite3_realloc is called with ~2 630 000 000, this value gives a
negative value because nAlloc is an int. In this case, sqlite3_realloc
releases the pointer.
Afterward in sqlite3_get_table at line 92643, this released pointer is used.
To fix i quickly added this line in sqlite3_get_table_cb before :
if( p->nData + need > p->nAlloc ){
char **azNew;
* if (p->nAlloc >
(int)(0x3fffffff/sizeof(char*)-need*sizeof(char*))) { goto
malloc_failed; }*
p->nAlloc = p->nAlloc*2 + need;
azNew = sqlite3_realloc( p->azResult, sizeof(char*)*p->nAlloc );
...
Do you think this fix is right ?
Is it necessary to apply the same fix in other places?
Thank you
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