[Bug libc/32164] New: PAM testsuite fails pam_deny test since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[Bug libc/32164] New: PAM testsuite fails pam_deny test since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

            Bug ID: 32164
           Summary: PAM testsuite fails pam_deny test since recent commit
                    (e24902f409994f226dbc6fde2476009df452a18f)
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: sam at gentoo dot org
                CC: drepper.fsp at gmail dot com, siddhesh at sourceware dot org
  Target Milestone: ---

Originally reported downstream in Gentoo at https://bugs.gentoo.org/939446.

PAM seems to fail its pam_deny test for 32-bit. The relevant code was added in
e24902f409994f226dbc6fde2476009df452a18f (ungetc: Fix backup buffer leak on
program exit [BZ #27821]').

Summarising my notes from over there:
```
/var/tmp/portage/sys-libs/pam-1.6.1/work/Linux-PAM-1.6.1-abi_x86_32.x86/modules/pam_deny
# libtool --mode=execute gdb --args ./tst-pam_deny-retval
Program received signal SIGSEGV, Segmentation fault.
0xf7da1312 in _IO_unbuffer_all () at genops.c:822
822           if (fp->_mode > 0 && _IO_have_wbackup (fp))
(gdb) bt
#0  0xf7da1312 in _IO_unbuffer_all () at genops.c:822
#1  _IO_cleanup () at genops.c:885
#2  0xf7d495b8 in __run_exit_handlers (status=<optimized out>, listp=<optimized
out>, run_list_atexit=<optimized out>, run_dtors=<optimized out>) at exit.c:129
#3  0xf7d49613 in __GI_exit (status=0) at exit.c:138
#4  0xf7d293d3 in __libc_start_call_main (main=main@entry=0x56556e50 <main>,
argc=argc@entry=1, argv=argv@entry=0xffffd314) at
../sysdeps/nptl/libc_start_call_main.h:74
#5  0xf7d29499 in __libc_start_main_impl (main=0x56556e50 <main>, argc=1,
argv=0xffffd314, init=0x0, fini=0x0, rtld_fini=0xf7fca2e0 <_dl_fini>,
stack_end=0xffffd30c)
    at ../csu/libc-start.c:360
#6  0x56556d27 in _start ()
```

```
0xf7da1312 in _IO_unbuffer_all () at genops.c:822
822           if (fp->_mode > 0 && _IO_have_wbackup (fp))
(gdb) p fp
$1 = (FILE *) 0xf7f6b700 <_IO_stdin_>
(gdb) p fp->_mode
$2 = 1
(gdb) p *fp
$3 = {_flags = -72540024, _IO_read_ptr = 0x0, _IO_read_end = 0x0, _IO_read_base
= 0x0, _IO_write_base = 0x0, _IO_write_ptr = 0x0, _IO_write_end = 0x0,
_IO_buf_base = 0x0,
  _IO_buf_end = 0x0, _IO_save_base = 0x0, _IO_backup_base = 0x0, _IO_save_end =
0x0, _markers = 0x0, _chain = 0x0, _fileno = 0, _flags2 = 0, _old_offset = -1,
_cur_column = 0,
  _vtable_offset = -72 '\270', _shortbuf = "", _lock = 0xf7f6c8d0
<_IO_stdfile_0_lock>, _offset = 4160138104, _codecvt = 0x0, _wide_data = 0x0,
_freeres_list = 0x0, _freeres_buf = 0x0,
  _prevchain = 0x0, _mode = 1, _unused2 = "\030\244UV", '\000' <repeats 35
times>}
(gdb) call _IO_have_wbackup(fp)
Cannot access memory at address 0x24
```

```
(gdb) info macro _IO_have_wbackup
Defined at /usr/src/debug/sys-libs/glibc-2.40-r1/glibc-2.40/libio/libioP.h:581
  included at
/usr/src/debug/sys-libs/glibc-2.40-r1/glibc-2.40/libio/genops.c:29
#define _IO_have_wbackup(fp) ((fp)->_wide_data->_IO_backup_base != NULL)
(gdb) p fp->_wide_data
$4 = (struct _IO_wide_data *) 0x0
(gdb) p fp->_IO_backup_base
$5 = 0x0
```

(In reply to Sam James from comment #4)
> ```
> 0xf7da1312 in _IO_unbuffer_all () at genops.c:822
> 822           if (fp->_mode > 0 && _IO_have_wbackup (fp))
> [...]

This was introduced in
https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=e24902f409994f226dbc6fde2476009df452a18f.
We pulled in this commit in sys-libs/glibc-2.40-r1 as it's on
release/2.40/master.

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[Bug libc/32164] PAM testsuite fails pam_deny test since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

--- Comment #1 from Sam James <sam at gentoo dot org> ---
I'm not likely to reduce this tonight. I might have time tomorrow but I need to
do some prep for cauldron still.

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[Bug libc/32164] PAM testsuite fails pam_deny test since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://sourceware.org/bugz
                   |                            |illa/show_bug.cgi?id=32137

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[Bug libc/32164] PAM testsuite fails pam_deny test since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

--- Comment #2 from Sam James <sam at gentoo dot org> ---
ae4d44b1d501421ad9a3af95279b8f4d1546f1ce ('libio: Attempt wide backup free only
for non-legacy code') isn't on the branch.

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[Bug libc/32164] PAM testsuite fails pam_deny test on releases/2.40 since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|PAM testsuite fails         |PAM testsuite fails
                   |pam_deny test since recent  |pam_deny test on
                   |commit                      |releases/2.40 since recent
                   |(e24902f409994f226dbc6fde24 |commit
                   |76009df452a18f)             |(e24902f409994f226dbc6fde24
                   |                            |76009df452a18f)

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[Bug libc/32164] PAM testsuite fails pam_deny test on release/2.40/master since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|PAM testsuite fails         |PAM testsuite fails
                   |pam_deny test on            |pam_deny test on
                   |releases/2.40 since recent  |release/2.40/master since
                   |commit                      |recent commit
                   |(e24902f409994f226dbc6fde24 |(e24902f409994f226dbc6fde24
                   |76009df452a18f)             |76009df452a18f)

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[Bug libc/32164] PAM testsuite fails pam_deny test on release/2.40/master since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

--- Comment #3 from Sam James <sam at gentoo dot org> ---
(In reply to Sam James from comment #2)
> ae4d44b1d501421ad9a3af95279b8f4d1546f1ce ('libio: Attempt wide backup free
> only for non-legacy code') isn't on the branch.

... and indeed it fixes it.

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[Bug libc/32164] PAM testsuite fails pam_deny test on release/2.40/master since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[siddhesh at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

--- Comment #4 from Siddhesh Poyarekar <siddhesh at sourceware dot org> ---
Thanks for doing the backports!

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[Bug libc/32164] PAM testsuite fails pam_deny test on release/2.40/master since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[fweimer at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

Florian Weimer <fweimer at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fweimer at redhat dot com
             Status|NEW                         |WAITING
              Flags|                            |security-

--- Comment #5 from Florian Weimer <fweimer at redhat dot com> ---
Sam, do you think we can close this? Thanks.

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[Bug libc/32164] PAM testsuite fails pam_deny test on release/2.40/master since recent commit (e24902f409994f226dbc6fde2476009df452a18f)

[sam at gentoo dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=32164

Sam James <sam at gentoo dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|WAITING                     |RESOLVED

--- Comment #6 from Sam James <sam at gentoo dot org> ---
I think we're good now. Many thanks.

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