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freetds - Re: [freetds] bsqldb SEGFAULT abend

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  • From: christos AT zoulas.com (Christos Zoulas)
  • To: FreeTDS Development Group <freetds AT lists.ibiblio.org>
  • Subject: Re: [freetds] bsqldb SEGFAULT abend
  • Date: Thu, 1 Apr 2010 09:01:08 -0400

On Mar 31, 8:19pm, jklowden AT freetds.org ("James K. Lowden") wrote:
-- Subject: Re: [freetds] bsqldb SEGFAULT abend

| Ronildo wrote:
| >
| > Program received signal SIGSEGV, Segmentation fault.
| > [Switching to Thread -1208239392 (LWP 20221)]
| > 0x00b5143d in realloc () from /lib/libc.so.6
| > (gdb) bt
| > #0 0x00b5143d in realloc () from /lib/libc.so.6
| > #1 0x00132379 in tds_get_data (tds=0x8097ad0, curcol=0x80cad10) at
| > token.c:2043
| > #2 0x0013265a in tds_process_row (tds=0x8097ad0) at token.c:2168
| > #3 0x00134989 in tds_process_tokens (tds=0x8097ad0,
| > #result_type=0xbf940188,
| > done_flags=0x0, flag=5384) at token.c:623
| > #4 0x00120a47 in dbnextrow (dbproc=0x8097360) at dblib.c:1994
| > #5 0x0804aae5 in main (argc=Cannot access memory at address 0x4
| > ) at bsqldb.c:514
|
| Well, that's bad. It looks to me like memory corruption, because all
| that's ever supposed to be stored in blob->textpointer is a pointer
| returned by malloc/realloc.
|
| One possibilty is that determine_adjusted_size() somehow returns a
| negative value, leading realloc() to ask for something huge. (There are
| quite a few places in the code where int is used where size_t would be
| preferable. This might be one.)
|
| One thing you could do is add
|
| assert(new_blob_size > 0);
|
| as soon as it's assigned. Also see MALLOC_CHECK_ in your realloc() man
| page.
|
| I consider any segment fault a serious error, and I very much wnat to get
| to the bottom of it. It will be hard to reproduce, though, even with the
| details you've provided. The more you're able to do on your end, the
| better.
|
| (Then again, it seems Frediano commits a fix everytime I make a speech
| like that....)
|

Run it through valgrind...

christos




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