Re: kern/40575: security.pax.aslr breaks tar -z

[Pierre Pronchery <khorben%defora.org@localhost>]

The following reply was made to PR kern/40575; it has been noted by GNATS.

From: Pierre Pronchery <khorben%defora.org@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/40575: security.pax.aslr breaks tar -z
Date: Wed, 4 Jan 2012 01:02:53 +0100

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                        Hi,
 
 in his problem report from February 7th 2009, Manuel Bouyer mentions a
 problem while decompressing archives through tar, while the
 "security.pax.aslr.global" sysctl is enabled.
 
 Although I confirm the issue on my systems (NetBSD/amd64, tracking
 either netbsd-5 or -current branches) I have to disagree with this
 statement:
 > This is only dependant on security.pax.aslr, other
 > security.pax settings have no influence.
 
 On both systems, enabling "security.pax.mprotect.global" (set to "1")
 seems to workaround the issue.
 
 For the record:
 
 =3D=3D=3D BEGIN PASTE =3D=3D=3D
 $ tar -tzf xscreensaver-5.14.tar.gz=20
 tar: End of archive volume 1 reached
 tar: Sorry, unable to determine archive format.
 $ ls -l tar.core=20
 -rw-------  1 khorben  wheel  200272 Jan  4 00:42 tar.core
 $ gdb tar tar.core=20
 GNU gdb 6.5
 Copyright (C) 2006 Free Software Foundation, Inc.
 GDB is free software, covered by the GNU General Public License, and you are
 welcome to change it and/or distribute copies of it under certain condition=
 s.
 Type "show copying" to see the conditions.
 There is absolutely no warranty for GDB.  Type "show warranty" for details.
 This GDB was configured as "x86_64--netbsd"...(no debugging symbols found)
 
 Reading symbols from /lib/libutil.so.7...(no debugging symbols found)...don=
 e.
 Loaded symbols for /lib/libutil.so.7
 Reading symbols from /lib/libc.so.12...(no debugging symbols found)...done.
 Loaded symbols for /lib/libc.so.12
 Reading symbols from /libexec/ld.elf_so...
 (no debugging symbols found)...done.
 Loaded symbols for /libexec/ld.elf_so
 Core was generated by `tar'.
 Program terminated with signal 11, Segmentation fault.
 #0  0x00007f7ffde03a74 in _rtld_bind_start () from /libexec/ld.elf_so
 (gdb) bt
 #0  0x00007f7ffde03a74 in _rtld_bind_start () from /libexec/ld.elf_so
 #1  0x000077ed06ddf000 in ?? ()
 #2  0x0000000000000021 in ?? ()
 #3  0x0000000000404583 in ar_start_gzip ()
 #4  0x000000000040481e in ar_open ()
 #5  0x0000000000407ea4 in rd_start ()
 #6  0x0000000000405456 in get_arc ()
 #7  0x000000000040580b in list ()
 #8  0x000000000040dde5 in main ()
 (gdb) info registers
 rax            0x0      0
 rbx            0x4168f1 4286705
 rcx            0x77ed06981dea   131859901586922
 rdx            0x9      9
 rsi            0x1      1
 rdi            0xa      10
 rbp            0x5      0x5
 rsp            0x7f7fff4abe78   0x7f7fff4abe78
 r8             0x101010101010101        72340172838076673
 r9             0x8080808080808080       -9187201950435737472
 r10            0x0      0
 r11            0x246    582
 r12            0x41809b 4292763
 r13            0x1a     26
 r14            0x7f7ffde04bf0   140187696909296
 r15            0x3      3
 rip            0x7f7ffde03a74   0x7f7ffde03a74 <_rtld_bind_start>
 eflags         0x10246  [ PF ZF IF RF ]
 cs             0x1f     31
 ss             0x17     23
 ds             0x17     23
 es             0x17     23
 fs             0x17     23
 gs             0x17     23
 (gdb)=20
 =3D=3D=3D END PASTE =3D=3D=3D
 (this is on NetBSD/amd64, tracking the netbsd-5 branch)
 
 HTH,
 --=20
 khorben
 
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