Re: [PATCH 15/16] linux: Add {f}stat{at} y2038 support

[Lukasz Majewski <lukma@denx.de>]

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Hi Adhemerval,

> On 13/10/2020 10:58, Lukasz Majewski wrote:
> > Hi Adhemerval,
> >   
> >> On 07/10/2020 09:52, Adhemerval Zanella wrote:  
> >>>
> >>>
> >>> On 06/10/2020 06:48, Lukasz Majewski wrote:    
> >>>> Hi Adhemerval,
> >>>>    
> >>>>> A new struct __stat{64}_t64 type is added with the required
> >>>>> __timespec64 time definition.  Both non-LFS and LFS support were
> >>>>> done with an extra __NR_statx call plus a conversion to the new
> >>>>> __stat{64}_t64 type.  The statx call is done only for
> >>>>> architectures with support for 32-bit time_t ABI.
> >>>>>
> >>>>> Internally some extra routines to copy from/to struct stat{64}
> >>>>> to struct __stat{64} used on multiple implementations (stat,
> >>>>> fstat, lstat, and fstatat) are added on a extra file
> >>>>> (stat_t64_cp.c).  Aslo some extra routines to copy from statx to
> >>>>> __stat{64} is added on statx_cp.c.
> >>>>>
> >>>>> Checked with a build for all affected ABIs. I also checked on
> >>>>> x86_64, i686, powerpc, powerpc64le, sparcv9, sparc64, s390, and
> >>>>> s390x.    
> >>>>
> >>>> When do you plan to pull this patch set to -master?
> >>>> Those patches have been available for review on the mailing list
> >>>> for more than two months now.    
> >>>
> >>> Hi Lukasz, thanks to remind me. I will rebase against master and
> >>> run some regressions tests against some platforms and push it.
> >>>     
> >>
> >> One required change with the rebase is adapt the riscv32 ABI to
> >> exclude the __{f,l}xstat{at} symbol and replace with proper
> >> {f,l}stat ones. It is possible because the new ABI was added on
> >> current development branch, however one minor inconvenient is the
> >> toolchain need to be rebuild with a updated glibc branch to avoid
> >> linking failures with libstd++ (which uses __{f,l}xstat{at}).
> >>  
> > 
> > I'm not sure if this is related, but on my ARMv7 (32 bit) sandbox
> > there is an issue with fstat accesses to files.
> > 
> > When I try to run a program build against newest glibc (installed in
> > /opt/lib) I do see issues with {f}stat on other libraries (e.g.
> > /opt/lib/librt.so). To be more specific I do experience the
> > EOVERFLOW error:
> > 
> > error while loading shared libraries: librt.so.1: cannot stat shared
> > object: Error 75
> > 
> > The "base" glibc is 2.28 (installed in /lib). The glibc under test
> > is the newest master installed in /opt/lib.
> > 
> > I'm now investigating this issue.  
> 
> I am not sure what it might be based on these information, could you
> provide a strace so we can pinpoint what might the issue?  

Things are getting more and more interesting.

Let's consider the /opt/lib/librt.so.1

After qemu boot:

root@y2038arm:~# stat /opt/lib/librt.so.1
  File: /opt/lib/librt.so.1 -> librt-2.32.9000.so
  Size: 18              Blocks: 0          IO Block: 4096   symbolic
link Device: b300h/45824d    Inode: 17490       Links: 1
Access: (0777/lrwxrwxrwx)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2020-10-13 23:14:56.800000000 +0000      ----> OK
Modify: 2020-10-13 23:14:52.770000000 +0000
Change: 2020-10-13 23:14:52.770000000 +0000

Then I do run gdb (which was build with 2.28 glibc as a base and gcc
8.1, which uses the same library):

gdb test_y2038:
...
(gdb) run
Starting program: /usr/bin/test_y2038
/usr/bin/test_y2038: error while loading shared libraries: librt.so.1:
cannot stat shared object: Error 75 [Inferior 1 (process 1045) exited
with code 0177]

So I've accessed the librt.so.1 with some old - i.e. 2.28 ABI - now:

root@y2038arm:~# stat /opt/lib/librt.so.1
  File: /opt/lib/librt.so.1 -> librt-2.32.9000.so
  Size: 18              Blocks: 0          IO Block: 4096   symbolic
link Device: b300h/45824d    Inode: 17490       Links: 1
Access: (0777/lrwxrwxrwx)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 1901-12-13 20:46:33.625721000 +0000  ----> Overflow
Modify: 2020-10-13 23:14:52.770000000 +0000
Change: 2020-10-13 23:14:52.770000000 +0000

root@y2038arm:~# strace -v -Tf -e trace=file test_y2038

openat(AT_FDCWD, "/opt/lib/librt.so.1", O_RDONLY|O_LARGEFILE|O_CLOEXEC)
= 3 <0.000409> statx(3, "",
AT_STATX_SYNC_AS_STAT|AT_NO_AUTOMOUNT|AT_EMPTY_PATH, STATX_BASIC_STATS,
{stx_mask=STATX_ALL, stx_blksize=4096, stx_attributes=0, stx_nlink=1,
stx_uid=0, stx_gid=0, stx_mode=S_IFREG|0755, stx_ino=17487,
stx_size=425008, stx_blocks=832,
stx_attributes_mask=STATX_ATTR_COMPRESSED|STATX_ATTR_IMMUTABLE|STATX_ATTR_APPEND|STATX_ATTR_NODUMP|STATX_ATTR_ENCRYPTED,
stx_atime={tv_sec=1602625090, tv_nsec=600000000} /*
2020-10-13T21:38:10.600000000+0000 */, stx_btime={tv_sec=1602622592,
tv_nsec=0} /* 2020-10-13T20:56:32+0000 */,
stx_ctime={tv_sec=2147484284, tv_nsec=335721000},
stx_mtime={tv_sec=2147484263, tv_nsec=545721000}, stx_rdev_major=0,
stx_rdev_minor=0, stx_dev_major=179, stx_dev_minor=0}) = 0 <0.000494>
test_y2038: error while loading shared libraries: librt.so.1: cannot
stat shared object: Error 75 +++ exited with 127 +++


Here the ctime and mtime are wrong - i.e. overflowed.

The system date is not changed:
root@y2038arm:~# date
Tue Oct 13 21:40:02 UTC 2020
root@y2038arm:~# date +%s
1602625224

I will continue investigation tomorrow...

> 
> The arm-linux-gnueabihf testing I did was on a aarch64 kernel
> (4.12.13). Besides the make check without regression, I could run
> system binaries with ./testrun.sh.
> 
> I will check on a different kernel/system with a 32-bit kernel.
> 




Best regards,

Lukasz Majewski

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