[Gluster-devel] glusterd crashes on /tests/bugs/replicate/bug-884328.t

[Xavi Hernandez]

On Fri, Dec 15, 2017 at 9:57 AM, Atin Mukherjee <amukherj at redhat.com> wrote:

> But why doesn't it crash every time if this is the RCA? None of us could
> actually reproduce it locally.
>

That's a good question. One of my patches has failed and it doesn't add any
new option (in fact it's a very trivial change), so I'm not sure why it may
or may not crash.

I'll analyze it. Anyway, that function needs a patch because there's no
space limit check before writing to the buffer.

Xavi


> On Fri, Dec 15, 2017 at 2:23 PM, Xavi Hernandez <jahernan at redhat.com>
> wrote:
>
>> I've seen this failure in one of my local tests and I've done a quick
>> analysis:
>>
>> (gdb) bt
>> #0  0x00007ff29e1fce07 in ?? () from /lib64/libgcc_s.so.1
>> #1  0x00007ff29e1fe9b8 in _Unwind_Backtrace () from /lib64/libgcc_s.so.1
>> #2  0x00007ff2aa9fb458 in backtrace () from /lib64/libc.so.6
>> #3  0x00007ff2ac14af30 in _gf_msg_backtrace_nomem (level=GF_LOG_ALERT,
>> stacksize=200) at logging.c:1128
>> #4  0x00007ff2ac151170 in gf_print_trace (signum=11, ctx=0xdec260) at
>> common-utils.c:762
>> #5  0x000000000040a2c6 in glusterfsd_print_trace (signum=11) at
>> glusterfsd.c:2274
>> #6  <signal handler called>
>> #7  0x00007ff2ac466751 in _dl_close () from /lib64/ld-linux-x86-64.so.2
>> #8  0x00007ff2aaa304df in _dl_catch_error () from /lib64/libc.so.6
>> #9  0x00007ff2ab35f715 in _dlerror_run () from /lib64/libdl.so.2
>> #10 0x00007ff2ab35f08f in dlclose () from /lib64/libdl.so.2
>> #11 0x00007ff2a06af786 in glusterd_get_volopt_content
>> (ctx=0x7ff298000d88, xml_out=false) at glusterd-utils.c:13150
>> #12 0x00007ff2a06a2896 in glusterd_volset_help (dict=0x70616e732d776f68,
>> op_errstr=0x732e736572757461) at glusterd-utils.c:9199
>> Backtrace stopped: previous frame inner to this frame (corrupt stack?)
>> (gdb) f 11
>> #11 0x00007ff2a06af786 in glusterd_get_volopt_content
>> (ctx=0x7ff298000d88, xml_out=false) at glusterd-utils.c:13150
>> 13150                           dlclose (dl_handle);
>> (gdb) print dl_handle
>> $1 = (void *) 0x6978656c7069746c
>> (gdb) x/s &dl_handle
>> 0x7ff294206500: "ltiplexing feature is disabled.\n\n"
>> (gdb)
>>
>> So I think the problem is a buffer overflow.
>>
>> Looking at the code in glusterd-utils.c, function
>> glusterd_get_volopt_content(), I guess that we are writing too much data
>> into output_string, which is a stack defined array of 50 KB, and we have an
>> overflow there. Probably the number of options and its description has
>> grown beyond this limit.
>>
>> I'll send a patch for this shortly.
>>
>> Xavi
>>
>> On Fri, Dec 15, 2017 at 8:31 AM, Sunny Kumar <sunkumar at redhat.com> wrote:
>>
>>> +1
>>>
>>> Console log
>>> https://build.gluster.org/job/centos6-regression/8021/console
>>>
>>> Regard
>>> Sunny
>>>
>>> On Fri, Dec 15, 2017 at 12:32 PM, Ravishankar N <ravishankar at redhat.com>
>>> wrote:
>>> > ...for a lot of patches on master .The crash is in volume set; the .t
>>> just
>>> > does a volume set help. Can the glusterd devs take a look as it is
>>> blocking
>>> > merging patches? I have raised BZ 1526268 with the details.
>>> >
>>> > Thanks!
>>> >
>>> > Ravi
>>> >
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>>
>>
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>
>
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