Re: [musl] runtime error: initgroups(www-data, 33) failed (5: I/O error)

[Static Php <phpstatic.com@gmail.com>]

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I am not sure which step I made wrong, but I still get this error.

1. make clean
2. make musl-1.2.1
3. patch -p1 < ../patches/musl-1.2.0/0002-group.diff
4. make all -j8
5. sudo make install

then I relink my php, test at  old server and get the same result.

On Sat, Oct 10, 2020 at 4:39 AM Rich Felker <dalias@libc.org> wrote:

> On Fri, Oct 02, 2020 at 10:37:03PM -0400, Rich Felker wrote:
> > On Sat, Oct 03, 2020 at 09:06:50AM +0800, Static Php wrote:
> > > I has this runtime error on Ubuntu 18.04.5 LTS, CPU is AMD EPYC
> Processor.
> > >
> > > Kernel: 5.4.0-49-generic #53~18.04.1-Ubuntu (other kernel also has this
> > > problem)
> > >
> > > more details: https://github.com/richfelker/musl-cross-make/issues/107
> > >
> > > strace:
> > >
> > > execve("./a.out", ["./a.out"], 0x7fff12cd26d0 /* 20 vars */) = 0
> > > >
> > > > arch_prctl(ARCH_SET_FS, 0x7ff53bb3b618) = 0
> > > >
> > > > set_tid_address(0x7ff53bb3bbe8)         = 40778
> > > >
> > > > socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0) = 3
> > > >
> > > > brk(NULL)                               = 0x555556f23000
> > > >
> > > > brk(0x555556f25000)                     = 0x555556f25000
> > > >
> > > > mmap(0x555556f23000, 4096, PROT_NONE,
> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS,
> > > > -1, 0) = 0x555556f23000
> > > >
> > > > mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
> -1, 0) =
> > > > 0x7ff53bb39000
> > > >
> > > > connect(3, {sa_family=AF_UNIX, sun_path="/var/run/nscd/socket"}, 24)
> = 0
> > > >
> > > > sendmsg(3, {msg_name=NULL, msg_namelen=0,
> > > > msg_iov=[{iov_base="\2\0\0\0\17\0\0\0\t\0\0\0", iov_len=12},
> > > > {iov_base="www-data\0", iov_len=9}], msg_iovlen=2, msg_controllen=0,
> > > > msg_flags=0}, MSG_NOSIGNAL) = 21
> > > >
> > > > readv(3, [{iov_base="\2\0\0\0\1\0\0\0\0\0\0", iov_len=11},
> {iov_base="\0",
> > > > iov_len=1024}], 2) = 12
> > > >
> > > > mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
> -1, 0) =
> > > > 0x7ff53bb38000
> > > >
> > > > close(3)                                = 0
> > > >
> > > > munmap(0x7ff53bb39000, 4096)            = 0
> > > >
> > > > munmap(0x7ff53bb38000, 4096)            = 0
> > > >
> > > > ioctl(1, TIOCGWINSZ, {ws_row=59, ws_col=225, ws_xpixel=1575,
> > > > ws_ypixel=826}) = 0
> > > >
> > > > writev(1, [{iov_base="err=-1, errno=5", iov_len=15}, {iov_base="\n",
> > > > iov_len=1}], 2err=-1, errno=5
> > > >
> > > > ) = 16
> > > >
> > > > exit_group(0)                           = ?
> > > >
> > > > +++ exited with 0 +++
> > > >
> >
> > Ah, this looks like a bug in musl causing a zero-groups response from
> > nscd to be interpreted as an error rather than success with no
> > members:
> >
> >       if (!fread(nscdbuf, sizeof(*nscdbuf)*resp[INITGRNGRPS], 1, f)) {
> >               if (!ferror(f)) errno = EIO;
> >               goto cleanup;
> >       }
> >
> > The problem is that this code was written assuming the fread call
> > returns 1 on success, but fread has a stupid corner case (which we
> > used to get wrong) where a zero-length read is required by the
> > standard to return 0 even though logically it should return nmemb.
> >
> > You can work around the problem by adding www-data to a useless dummy
> > group. I'll prepare a patch for musl, though, and post it here as a
> > follow-up soon.
> >
> > Thanks for the report!
>
> I think the attached patch should work, but it's not tested since I
> dont have an environment with nscd handy.
>
> Rich
>

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