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From bugzi...@apache.org
Subject [Bug 55849] httpd child crashes in ct_auth_check_user
Date Thu, 05 Dec 2013 17:48:12 GMT
https://issues.apache.org/bugzilla/show_bug.cgi?id=55849

--- Comment #2 from Siva <sivasankar.manu@gmail.com> ---
(In reply to Jeff Trawick from comment #1)
> Is this ct_* stuff RSA ClearTrust?  If so, report it to them.
> 
> This third-party module passed NULL to fprintf() and crashed.  We can't
> handle it here.
> 
> Thread 1 is stuck in read(); it can't segfault.  (I think something that
> httpd is doing with signals may trigger a common mis-identification of
> thread 1 by pflags.)

Hi Jeff,

In such case, in the same server but with different user and application having
the same problem.
Below are the findings;

STEP1:

Run pflags and look for signals that caused a crash. Here I found a SIGSEGV
signal.

bash-3.2$ pflags core
core 'core' of 24067:   /dinftksw/apache2/bin/httpd -f
/dinftksw/apache2/conf/httpd.conf
        data model = _ILP32  flags = MSACCT|MSFORK
 /1:    flags = 0
        sigmask = 0xffffbefc,0x0000ffff  cursig = SIGSEGV

We have only one thread and crash occured in thread number 1

STEP2:
Do pstack and look for the thread one. I got below out put for thread one

bash-3.2$ pstack core
core 'core' of 24067:   /dinftksw/apache2/bin/httpd -f
/dinftksw/apache2/conf/httpd.conf
 fee013f0 fprintf  (0, fe955128, fe9c6148, a1010, fe7ffe04, 7ffffffe) + 24
 fe7fd8b4 ct_uprint_private (4, ffbfd5f8, 1, 1, ff00, ff0000) + 210
 fe7fda64 ct_debug_uprintln (fe93d150, 1e14, 35b, fe93d4d0, 0, 0) + 24
 fe78f39c ct_child_process_init (19d7b0, 10cf70, 2, 0, 10cf70, 192aa8) + 70
 00043680 ap_run_child_init (19d7b0, 10cf70, 0, feaa8, 0, 103228) + 40
 000adeec child_main (0, acc6c, 0, 0, feea79a0, fed12a00) + 7c
 000ae2c0 make_child (f7000, 0, 1, fa000, f6400, f9c00) + 128
 000aeaf0 ap_mpm_run (fe5c00a8, 9, 0, 10, 1, 32) + 740
 00030784 main     (104a80, f4800, f7000, f7000, 102a78, 0) + 774
 0002fb40 _start   (0, 0, 0, 0, 0, 0) + 5c

The function fprintf is causing the crash. It is located in memory address
fee013f0.


STEP3:

Do the pmap and search for that near for that address
bash-3.2$ pmap core >pmap.txt

bash-3.2$ ls -lrt pmap.txt
-rw-r-----   1 dinftksw dinftk      5357 Dec  4 12:26 pmap.txt

bash-3.2$ grep -i "fee" pmap.txt
FEE90000       8K r-x--  /lib/libc.so.1
FEEA2000      40K rwx--  /lib/libc.so.1
FEEAC000       8K rwx--  /lib/libc.so.1
FEEB0000     576K r-x--  /lib/libnsl.so.1


Please help me to know right contact details if it is not the right place to
discuss above issue

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