coredump in free on solaris

dayalan_cse · 11-22-2007, 04:54 AM

Hello,

I am using Solaris 9/sparc64, I ran my code on sparc, compiled using cc 5.2 update 1 version. it crashes when it tries to free() a string variable (pointer variable for a string) and to narrow down the issue i print the address and string before doing free(p), it has proper address and string it got displayed in the STDOUT but when it tries to free that pointer it crashes.

Please let me know your inputs to resolve this issue.

Thanks,
Dayalan

bigearsbilly · 11-22-2007, 05:51 AM

er, you've done something wrong.
it is not a valid address for free.
there is no other answer.

that's all we have to go on.

dayalan_cse · 11-22-2007, 09:03 AM

Quote:

Originally Posted by bigearsbilly

er, you've done something wrong.
it is not a valid address for free.
there is no other answer.

that's all we have to go on.

Hi,

thanks for the inputs, intersting information is sometimes it crashes int the same machine and sometimes its not. here is the stack trace.

==================================================================

waitid (0, 2ee, ffbfc570, 103)
fc759460 _waitpid (2ee, ffbfc65c, 100, fffffff8, ffffffe0, ffbfc6cd) + 5c
fc7959bc system (ffbfc840, fe251bf0, fe7a6c4c, 2eb, fee9e400, fe7a61c8) + 240
fd923824 fatal_handler (fe251800, 0, ffbfcb00, fe7a6c00, fe251800, 1) + 70
fc79fb9c sigacthandler (b, 0, ffbfcb00, 10c488, 66aee8, fc419380) + 28
--- called from signal handler with signal 11 (SIGSEGV) ---
fc747620 realfree (66aef0, fc7c2994, fc7c2994, 16, 16, fc589778) + 74
fc747e60 _free_unlocked (313cb0, 74264, 20ee4, fc7bc000, 0, 0) + 98
fc747db8 free (313cb0, fc56b890, 6ef, 421ec, fc5350a4, 0) + 20

==================================================================

As you said its i am doing something mistake here, how to make sure that is the issue is from my function or is it from free() (libc) from sun?

Thanks
Dayalan

crisostomo_enrico · 11-22-2007, 09:20 AM

Well, without seeing any code... I'd naturally guess that something is wrong with the code rather than with a library. Bugs related with memory management may be subtle and your code may or may not crash immediately, that's not a proof.

Can you show us the code?

dayalan_cse · 11-22-2007, 09:35 AM

Quote:

Originally Posted by crisostomo_enrico

Well, without seeing any code... I'd naturally guess that something is wrong with the code rather than with a library. Bugs related with memory management may be subtle and your code may or may not crash immediately, that's not a proof.

Can you show us the code?

I knew there are some debuggers for especially for memories those are valgrind and mcheck available only on Linux boxes, But the problem i am facing here in Solaris.

Can anybody suggest are there any kind of tools are available for memory debugging on Solaris (like in Linux Boxes).

Please let me know.

Thanks,
Dayalan

jlliagre · 11-22-2007, 04:10 PM

Quote:

Originally Posted by dayalan_cse

Can anybody suggest are there any kind of tools are available for memory debugging on Solaris (like in Linux Boxes).

Sun studio 12 dbx has an excellent memory debugger. It's called RTC (run time checking). http://docs.sun.com/app/docs/doc/819-5257/blahb?a=view

dayalan_cse · 11-22-2007, 11:34 PM

Quote:

Originally Posted by jlliagre

Sun studio 12 dbx has an excellent memory debugger. It's called RTC (run time checking). http://docs.sun.com/app/docs/doc/819-5257/blahb?a=view

Hello,

Thank you for the inputs.

Another observation on this issue is, I see some times application not getting crash (it ran fine) but sometimes (not predictable) it crashes.

Any ideas why it is happening like this?

Thanks,
Dayalan

jlliagre · 11-23-2007, 01:39 AM

Quote:

Originally Posted by dayalan_cse

Another observation on this issue is, I see some times application not getting crash (it ran fine) but sometimes (not predictable) it crashes.

Any ideas why it is happening like this?

Yes. Random crashes is a typical behavior observed with memory buggy applications.

Your code or one of the libraries you use are probably messing with parts of memory located slightly outside the allocated areas.

dayalan_cse · 11-23-2007, 05:17 AM

Quote:

Originally Posted by jlliagre

Yes. Random crashes is a typical behavior observed with memory buggy applications.

Your code or one of the libraries you use are probably messing with parts of memory located slightly outside the allocated areas.

I am not understanding, Can you please elborate little bit, I would like ot understand the issue.

jlliagre · 11-23-2007, 06:25 AM

Please read the page I posted a link to. There are examples of memory programming mistakes.

eg:

Code:

char *a = (char *)malloc(1);
a[1] = ”\0’;

dayalan_cse · 11-23-2007, 10:33 PM

Quote:

Originally Posted by jlliagre

Please read the page I posted a link to. There are examples of memory programming mistakes.

eg:

Code:

char *a = (char *)malloc(1);
a[1] = ”\0’;

dbx is not able to find out the memory bug so my application runs fine under dbx or gdb.

how to enable "memory debug all kind of check related with memory" under dbx?

Thanks,
Dayalan

jlliagre · 11-24-2007, 01:18 AM

Here is how to enable all of them:

Code:

$ dbx yourProgram
(dbx) check -all
(dbx) run
...

dayalan_cse · 11-24-2007, 05:43 AM

Quote:

Originally Posted by jlliagre

Here is how to enable all of them:

Code:

$ dbx yourProgram
(dbx) check -all
(dbx) run
...

I used "check -all" under dbx but it is not useful because it is not able to find the issue but when i ran same application from shell it crashes.

please let me know your inputs.

Thanks,
Dayalan

jlliagre · 11-24-2007, 08:23 AM

Another way to track memory issues with Solaris is using libumem.

http://developers.sun.com/solaris/ar...m_library.html

http://blogs.sun.com/peteh/entry/hid...umem_firewalls

dayalan_cse · 11-25-2007, 04:27 AM

Quote:

Originally Posted by jlliagre

Another way to track memory issues with Solaris is using libumem.

http://developers.sun.com/solaris/ar...m_library.html

http://blogs.sun.com/peteh/entry/hid...umem_firewalls

Hi,

my observation is when i ran application directly from shell it crashes so i set LD_PRELOAD = libumem.so.1 and UMEM_DEBUG = default then i ran the application the ran fine.

I cant predict where the issue is? [ from kernel? or from application? ]

One more question, how to core files using gcore command, to run gcore it requires "pid" but when ran the application it ran fastly so i could not find "pid". please let me know.

thanks for your inputs.

Thanks,
Dayalan