SIGSEGV of useradd (from shadow package)

It seems to be easy to crash useradd (from shadow package).

# ls -l $(which useradd)

lrwxrwxrwx 4 root guixbuild 69 Jan 1 1970 /root/.guix-profile/sbin/useradd -> /gnu/store/ylnc73apl1irl0s613rxjl445x2zx8a5-shadow-4.2.1/sbin/useradd

# useradd test

Neoprávn?ný p?ístup do pam?ti (SIGSEGV) (core dumped [obraz pam?ti ulo?en])

(139) # gdb $(which useradd) core

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Reading symbols from /root/.guix-profile/sbin/useradd...(no debugging symbols found)...done.

[New LWP 1603]

warning: Could not load shared library symbols for linux-vdso.so.1.

Do you need "set solib-search-path" or "set sysroot"?

Core was generated by `useradd test'.

Program terminated with signal SIGSEGV, Segmentation fault.

#0 0x00007f457ee6503c in call_init.part () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

(gdb) bt

#0 0x00007f457ee6503c in call_init.part () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

#1 0x00007f457ee65205 in _dl_init () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

#2 0x00007f457ee696a0 in dl_open_worker () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

#3 0x00007f457ee64f34 in _dl_catch_error () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

#4 0x00007f457ee68d33 in _dl_open () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

#5 0x00007f457e841fb9 in dlopen_doit () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libdl.so.2

#6 0x00007f457ee64f34 in _dl_catch_error () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/ld-linux-x86-64.so.2

#7 0x00007f457e842589 in _dlerror_run () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libdl.so.2

#8 0x00007f457e842051 in dlopen@@GLIBC_2.2.5 () from /gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libdl.so.2

#9 0x00007f457ea49e8d in _pam_load_module () from /gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam.so.0

#10 0x00007f457ea4a4f9 in _pam_add_handler () from /gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam.so.0

#11 0x00007f457ea4ad90 in _pam_parse_conf_file () from /gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam.so.0

#12 0x00007f457ea4b395 in _pam_init_handlers () from /gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam.so.0

#13 0x00007f457ea4cae1 in pam_start () from /gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam.so.0

#14 0x0000000000403351 in main ()

Interesting information about module causing it would be in stackframe

#9 but there are no debugging information available. Adding debug

`output' to linux-pam would diverge me from GuixSD.

from strace:

read(3, "account required pam_deny.so \nau"..., 4096) = 223

open("/gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/security/pam_deny.so", O_RDONLY|O_CLOEXEC) = 5

read(5, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\340\6\0\0\0\0\0\0"..., 832) = 832

fstat(5, {st_mode=S_IFREG|0555, st_size=6728, ...}) = 0

mmap(NULL, 2100200, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 5, 0) = 0x7fb8b447c000

mprotect(0x7fb8b447d000, 2093056, PROT_NONE) = 0

mmap(0x7fb8b467c000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 5, 0) = 0x7fb8b467c000

close(5) = 0

--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x7fb8b3d1bda8} ---

+++ killed by SIGSEGV (core dumped) +++

# cat /etc/pam.d/useradd

account required pam_unix.so

auth sufficient pam_rootok.so

password required pam_unix.so

session required /gnu/store/4mmn5y6syzv7wwz1y6bl1ab4g0yvkdq1-elogind-219.14/lib/security/pam_elogind.so

session required pam_unix.so

# cat /etc/pam.d/other

account required pam_deny.so

auth required pam_deny.so

password required pam_deny.so

session required /gnu/store/4mmn5y6syzv7wwz1y6bl1ab4g0yvkdq1-elogind-219.14/lib/security/pam_elogind.so

session required pam_deny.so

Hello!

Tomáš ?ech <sleep_walker@gnu.org> skribis:

Is it on GuixSD?

Could you check in the ‘strace’ output whether PAM modules build with

another libc are being loaded?

Thanks for your report!

Ludo’.

On Wed, Aug 03, 2016 at 06:56:19PM +0200, Ludovic Courtès wrote:

Yes. \o/

It doesn't seem to be that case:

# grep linux-pam ~/useradd.strace | grep -v ENOENT

19555 open("/gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam_misc.so.0", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/libpam.so.0", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/security/pam_unix.so", O_RDONLY|O_CLOEXEC) = 4

19555 open("/gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/security/pam_rootok.so", O_RDONLY|O_CLOEXEC) = 4

19555 stat("/gnu/store/m4xna3zq2il5an61wxbmfv82ndvz70f6-linux-pam-1.2.1/lib", {st_mode=S_IFDIR|0555, st_size=4096, ...}) = 0

19555 open("/gnu/store/2xmwkq2ycwk89xlxnvib5wnjaacfy0rg-linux-pam-1.2.1/lib/security/pam_deny.so", O_RDONLY|O_CLOEXEC) = 5

On the other hand it seems to load part of the libraries from 2.22,

part from 2.23 and that is not healthy.

# grep glibc ~/useradd.strace | grep -v ENOENT

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libc.so.6", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libnss_compat.so.2", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libnsl.so.1", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libnss_nis.so.2", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libnss_files.so.2", O_RDONLY|O_CLOEXEC) = 3

19555 open("/gnu/store/8m00x5x8ykmar27s9248cmhnkdb2n54a-glibc-2.22/lib/libcrypt.so.1", O_RDONLY|O_CLOEXEC) = 4

19555 stat("/gnu/store/m9vxvhdj691bq1f85lpflvnhcvrdilih-glibc-2.23/lib", {st_mode=S_IFDIR|0555, st_size=4096, ...}) = 0

19555 open("/gnu/store/m9vxvhdj691bq1f85lpflvnhcvrdilih-glibc-2.23/lib/libm.so.6", O_RDONLY|O_CLOEXEC) = 4

19555 open("/gnu/store/m9vxvhdj691bq1f85lpflvnhcvrdilih-glibc-2.23/lib/librt.so.1", O_RDONLY|O_CLOEXEC) = 4

19555 open("/gnu/store/m9vxvhdj691bq1f85lpflvnhcvrdilih-glibc-2.23/lib/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 4

It seems to be more serious than I thought:

# login

Neoprávn?ný p?ístup do pam?ti (SIGSEGV) (core dumped [obraz pam?ti ulo?en])

S_W

Hi,

Tomáš ?ech <sleep_walker@gnu.org> skribis:

Indeed, this cannot work. Do you still have this problem? Do you know

why both libc versions were being used (LD_LIBRARY_PATH or some such?)?

TIA,

Ludo’.

tags 24138 moreinfo

Hi Tomáš,

Any updates on this bug, or should we close it?

https://bugs.gnu.org/24138

Thanks in advance! :-)

Ludo’.

ludo@gnu.org (Ludovic Courtès) skribis:

On Tue, 31 Jan 2017 23:25:32 +0100,

Ludovic Courtès wrote:

I haven't met this bug since. Let's close it.

Thanks.

S_W