[yocto] gdb built with musl libc segfault

[Lluis Campos]

Hi again,

On 04.04.2019 12:58, Lluis Campos wrote:
>
> On 03.04.2019 18:59, Khem Raj wrote:
>> On Tue, Apr 2, 2019 at 4:51 AM Lluis Campos 
>> <lluis.campos at northern.tech> wrote:
>>> Hi all,
>>>
>>> This is my very first question in the Yocto mailing list. Very exited!
>>> Please let me know if I should use other list for this.
>>>
>>>
>>> I am building an image using musl libc instead of gnu libc. I am not
>>> using yocto-tiny distro, instead I achieve this by setting on my 
>>> local.conf:
>>>
>>> TCLIBC = "musl"
>>>
>>>
>>> My app (mender) got a segfault just starting. See output from strace:
>>>
>>> root at raspberrypi3:~# strace mender
>>> execve("/usr/bin/mender", ["mender"], 0x7ee65e10 /* 13 vars */) = 0
>>> set_tls(0x76f1bffc)                     = 0
>>> set_tid_address(0x76f1bfa0)             = 3020
>>> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_ACCERR, 
>>> si_addr=0x530bc8} ---
>>> +++ killed by SIGSEGV +++
>>> Segmentation fault
>>>
>>>
>>> To be able to debug the process, I added gdb to my image adding to my
>>> local.conf:
>>>
>>> CORE_IMAGE_EXTRA_INSTALL += "packagegroup-core-buildessential
>>> packagegroup-core-tools-debug"
>>>
>>>
>>> Then, ironically, gdb itself also segfaults:
>>>
>>> root at raspberrypi3:~# strace gdb 2>&1 | tail
>>> fcntl64(3, F_SETFD, FD_CLOEXEC)         = 0
>>> getdents64(3, /* 6 entries */, 2048)    = 144
>>> getdents64(3, /* 0 entries */, 2048)    = 0
>>> close(3)                                = 0
>>> ioctl(0, TIOCGWINSZ, {ws_row=25, ws_col=74, ws_xpixel=0, 
>>> ws_ypixel=0}) = 0
>>> getcwd("/home/root", 4096)              = 11
>>> access("/usr/local/bin/gdb", X_OK)      = -1 ENOENT (No such file or
>>> directory)
>>> access("/usr/bin/gdb", X_OK)            = 0
>>> --- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, 
>>> si_addr=0x7e35aff0} ---
>>> +++ killed by SIGSEGV +++
>>>
>>>
>>> So, what is going on here? My guess is that some recipes are being
>>> wrongly linked with gnu libc instead of musl, and then cannot run in my
>>> device.
>>>
>>> Any ideas on how to debug the issue?
>>>
>> We have switched to using PIE by default in last few releases, can you
>> try master but comment out
>> require conf/distro/include/security_flags.inc
>> in your distro conf file.
>
> Hi Khem,
>
> Thanks for your help.
>
> Commenting out this line seems to work!


FYI,

Enabling back the require of security_flags.in, and instead applying no 
security flags only to my recipe is enough.

I have added to my conf/local.conf:

SECURITY_CFLAGS_pn-mender = "${SECURITY_NOPIE_CFLAGS}"
SECURITY_LDFLAGS_pn-mender = ""

So I will continue this way until I find the root cause on my CGO code.

Thanks again for your help.



>
> I will try to figure out exactly which exact option is causing the issue.
>
>
>>
>>> Thanks!
>>>
>>>
>>> Lluís Campos
>>> mender.io
>>> Northen Tech
>>>
>>> -- 
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>>> yocto at yoctoproject.org
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