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Date:      Tue, 19 Jul 2016 12:30:52 +0000
From:      bugzilla-noreply@freebsd.org
To:        freebsd-bugs@FreeBSD.org
Subject:   [Bug 211225] [PATCH]: CRASH: telnetd crashes periodically
Message-ID:  <bug-211225-8@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D211225

            Bug ID: 211225
           Summary: [PATCH]: CRASH: telnetd crashes periodically
           Product: Base System
           Version: 10.3-STABLE
          Hardware: Any
                OS: Any
            Status: New
          Keywords: patch
          Severity: Affects Only Me
          Priority: ---
         Component: bin
          Assignee: freebsd-bugs@FreeBSD.org
          Reporter: marcus@FreeBSD.org
          Keywords: patch

Created attachment 172719
  --> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=3D172719&action=
=3Dedit
Patch to fix telnetd crash

Yes, I still have telnetd running (though I don't use it).  Periodically, it
crashes.  I've tracked this down to a NULL pointer defref.  Attached is a p=
atch
that fixes the crash.

The backtrace I see is:

#0  0x0000000000405657 in telrcv () at
/usr/src/libexec/telnetd/../../contrib/telnet/telnetd/state.c:231
231                                             ch =3D *slctab[SLC_EL].sptr;
(gdb) bt
#0  0x0000000000405657 in telrcv () at
/usr/src/libexec/telnetd/../../contrib/telnet/telnetd/state.c:231
#1  0x000000000040a149 in ttloop () at
/usr/src/libexec/telnetd/../../contrib/telnet/telnetd/utility.c:88
#2  0x0000000000407055 in doit (who=3D0x7fffffffeb90)
    at /usr/src/libexec/telnetd/../../contrib/telnet/telnetd/telnetd.c:510
#3  0x0000000000407aa8 in main (argc=3D<value optimized out>,
argv=3D0x7fffffffec98)
    at /usr/src/libexec/telnetd/../../contrib/telnet/telnetd/telnetd.c:413
(gdb) print slctab
$1 =3D {{defset =3D {flag =3D 0 '\0', val =3D 0 '\0'}, current =3D {flag =
=3D 0 '\0', val =3D
0 '\0'},=20
    sptr =3D 0x0} <repeats 31 times>}
(gdb) print *slctab
$2 =3D {defset =3D {flag =3D 0 '\0', val =3D 0 '\0'}, current =3D {flag =3D=
 0 '\0', val =3D 0
'\0'}, sptr =3D 0x0}
(gdb) print *slctab[SLC_EL]
No symbol "SLC_EL" in current context.
(gdb) print *slctab[11]=20=20=20=20
Structure has no component named operator*.
(gdb) print slctab[11]
$3 =3D {defset =3D {flag =3D 0 '\0', val =3D 0 '\0'}, current =3D {flag =3D=
 0 '\0', val =3D 0
'\0'}, sptr =3D 0x0}
(gdb) print *slctab[11]
Structure has no component named operator*.
(gdb) print *slctab[11].sptr
Cannot access memory at address 0x0

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