From: Florian Weimer <fweimer@redhat.com>
To: Jacob Kroon <jacob.kroon@gmail.com>
Cc: Jacob Kroon via Gdb <gdb@sourceware.org>
Subject: Re: Debugging ld.so in gdb
Date: Fri, 04 Feb 2022 18:15:09 +0100 [thread overview]
Message-ID: <878ruqo8o2.fsf@oldenburg.str.redhat.com> (raw)
In-Reply-To: <06f726f4-855e-239b-fd2c-8d0d57f45131@gmail.com> (Jacob Kroon's message of "Fri, 4 Feb 2022 18:11:10 +0100")
* Jacob Kroon:
>> Interesting. Can you figure out where *rpo points right before things
>> go wrong? If the debuginfo doesn't work, this should do it:
>>
>> print (void *)$rax - 8
>>
>
> This is what I get:
>
>> (gdb) record goto 225037
>> Go backward to insn number 225037
>> #0 dfs_traversal (rpo=rpo@entry=0x7fffffffd3b0, map=0x7ffff7fad590, do_reldeps=do_reldeps@entry=0x0) at dl-sort-maps.c:175
>> 175 **rpo = map;
>> (gdb) print *rpo
>> $13 = (struct link_map **) 0x7fffffffd2c8
>> (gdb) print (void *)$rax - 8
>> $14 = (void *) 0x7fffffffd2c8
I wonder where 0x7fffffffd2c8 is located. Maybe on the minimal malloc
heap?
>> Maybe also look at map->l_name at this point, and further up the stack,
>> in dl_sort_maps, at maps and nmaps. It looks like we run off the end of
>> the array and write garbage to other areas of the process. 8-(
>>
>
> And this:
>
>> (gdb) print map->l_name
>> $15 = 0x7ffff7fad500 "/tmp/ramdisk/jacob-linux-master-glibc/work/x86_64-linux/icedtea7-native/2.1.3-r1.0/icedtea-2.1.3/build/openjdk.build-boot/lib/amd64/libjava.so"
>
> I couldn't find the other variables, maybe I need to get more acquainted
> with the sourcecode here.
I think you have to enter “up” a couple of times.
I suspect we are writing beyond the start of the array passed to
_dl_sort_maps.
Thanks,
Florian
next prev parent reply other threads:[~2022-02-04 17:15 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 13:45 Jacob Kroon
2022-02-04 13:58 ` Florian Weimer
2022-02-04 14:09 ` Jacob Kroon
2022-02-04 14:22 ` Florian Weimer
2022-02-04 14:27 ` Jacob Kroon
2022-02-04 16:09 ` Florian Weimer
2022-02-04 16:53 ` Jacob Kroon
2022-02-04 17:04 ` Florian Weimer
2022-02-04 17:11 ` Jacob Kroon
2022-02-04 17:15 ` Florian Weimer [this message]
2022-02-07 8:36 ` Jacob Kroon
2022-02-07 11:46 ` Jacob Kroon
2022-02-07 11:55 ` Florian Weimer
2022-02-07 12:15 ` Jacob Kroon
2022-02-07 12:27 ` Florian Weimer
2022-02-07 12:32 ` Jacob Kroon
2022-02-07 13:39 ` Jacob Kroon
2022-02-07 13:45 ` Jacob Kroon
2022-02-07 13:53 ` Adhemerval Zanella
2022-02-07 13:54 ` Jacob Kroon
2022-02-07 14:07 ` Florian Weimer
2022-02-07 16:28 ` Florian Weimer
2022-02-07 17:04 ` Jacob Kroon
2022-02-04 14:45 ` Jacob Kroon
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