Re: URGENT: Apache HTTP Migration from 1.3 to 2.4 UNIX Solaris

[William A Rowe Jr <wrowe@xxxxxxxxxxxxx>]

On Tue, Jan 8, 2019 at 10:48 AM <singhal.ankit@xxxxxxx> wrote:

I have migrated a user module mod_example from 1.3 to 2.4. But when I try to start the apache it is giving a segmentation fault and creating a core.

Following is the stacktrace while debug:
t@1 (l@1) signal SEGV (no mapping at the fault address) in strlen at 0xfefcceb8
0xfefcceb8: strlen+0x0018:      ldub     [%o2], %o1
Current function is apr_pstrdup
   77       len = strlen(s) + 1;
(dbx) where
current thread: t@1
  [1] strlen(0x1, 0xed568, 0x1, 0xed558, 0x1, 0x0), at 0xfefcceb8
=>[2] apr_pstrdup(a = 0xb8190, s = 0x1 "<bad address 0x00000001>"), line 77 in "apr_strings.c"
  [3] ap_add_module_commands(m = 0xfebc80d8, p = <value unavailable>), line 546 in "config.c"
  [4] ap_add_module(m = 0xfebc80d8, p = 0xb8190, sym_name = <value unavailable>), at 0x5db30
  [5] ap_add_loaded_module(mod = 0xfebc80d8, p = 0xb8190, short_name = 0xed510 "example_module"), line 713 in "config.c"
  [6] load_module(cmd = 0xffbfec90, dummy = <value unavailable>, modname = 0xed510 "example_module", filename = <value unavailable>), line 302 in "mod_so.c"

This is happening while loading a user module that I created:
LoadModule example_module modules/mod_example.so

Please provide your valuable insight into it so that I can go forward.

The info above is a bit limited in diagnosing the specifics of source code

you didn't share, and we aren't that great at divining the invisible, so two

thoughts for you; first build an httpd/apr/your module with CFLAGS -g -O0.

Sometimes you can only reproduce a crash with an optimized build, but 

the -g flag always remains useful in this regard (and objcopy can strip 

those symbols for general distribution.) I'm guessing the above was built 

with '-g' but with some '-O', optimizing out some of the args that might 

have been helpful.

Since we can't see above which command in your command_rec array

caused this segfault, we can see you had an invalid string element. 

Line 546 of config.c tripped over your input. config.c:546 was trying to;

        dir = apr_pstrdup(tpool, cmd->name);

This suggests you added a command to the list without an actual char*

string name value.

Compare your command_rec list with the templates of the various 

AP_INIT_* macros to ensure you provided valid initializers... only 

static const array values. Ensure you NULL terminate that list.