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

[Xavi Hernandez]

I've uploaded a patch to fix this problem: https://review.gluster.org/19040

On Fri, Dec 15, 2017 at 11:33 AM, Xavi Hernandez <jahernan at redhat.com>
wrote:

> I've checked the size of 'gluster volume set help' on current master and
> it's 51176 bytes. Only 24 bytes below the size of the buffer.
>
> I think the reason why regression tests fail is that it enables bd xlator,
> which adds some more options that make the help output to grow beyond the
> buffer size.
>
> I'll send a patch to fix the problem.
>
> Xavi
>
> On Fri, Dec 15, 2017 at 10:05 AM, Xavi Hernandez <jahernan at redhat.com>
> wrote:
>
>> 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
>>>>> >
>>>>> > _______________________________________________
>>>>> > Gluster-devel mailing list
>>>>> > Gluster-devel at gluster.org
>>>>> > http://lists.gluster.org/mailman/listinfo/gluster-devel
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>>>>> Gluster-devel mailing list
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>>>>>
>>>>
>>>>
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>>>
>>>
>>
>
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