On Tue, Jan 8, 2019 at 10:48 AM <singhal.an...@tcs.com> 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.
