Subject: Re: bug#13588: Pax hangs in case big UID

From: Stefano Lattarini <[email-masked]>
Date: Tue, 23 Apr 2013 10:45:43 +0200

On 04/22/2013 03:55 PM, Stefano Lattarini wrote:
> Hi Peter, thanks for the feedback.
> 
> On 04/22/2013 03:21 PM, Petr Hracek wrote:
>> Hello Stefano,
>>
>> thanks for the patch. All is working properly.
>> User is informed that UID is not enough smaller and configure script does not failed.
>>
> Good to know the logic is sound.  However, I now notice that there
> is still a problem with the output of configure :-/  (details below).
> 
>> Result is below:
>> test@localhost: ~/mycproject$ id
>> uid=17000000(test) gid=1001(test) groups=1001(test) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
>> test@localhost: ~/mycproject$ ./configure
>> checking for a BSD-compatible install... /usr/bin/install -c
>> checking whether build environment is sane... yes
>> checking for a thread-safe mkdir -p... /usr/bin/mkdir -p
>> checking for gawk... gawk
>> checking whether make sets $(MAKE)... yes
>> checking how to create a ustar tar archive... checking whether UID '17000000' is small enough for ustar... no
>> none
>>
> Oops, there are two messages are crossing.  This is bad.
> I think the best solution at this point is simply to report the too-high UID
> only in the generated config.log rather than in the console output.  Updated
> patch coming up soonish (I hope)...
> 
Here it is.  I'd appreciate further testing, if possible.

Thanks,
  Stefano

---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ---- 8< ----

>From bfb877d2337acfe3af1ef0d6e405f834a9287a37 Mon Sep 17 00:00:00 2001
Message-Id: <bfb877d23[email-masked]>
From: Stefano Lattarini <[email-masked]>
Date: Sun, 17 Feb 2013 16:42:46 +0100
Subject: [PATCH] tar: pax could hang configure when big UID are involved

See automake bug#8343 and bug#13588.

Tom Rini [email-masked] says (in bug#8343):

    When the user has a UID or GID that is larger than the ustar format
    supports, pax does not error out gracefully in some cases (FC13).

Marc Herbert <[email-masked]> adds (in bug#8343):

    When "configure" is run by a user with an UID bigger than 21 bits,
    BSD pax 3.4 aborts when trying to create the 'conftest.tar' test
    archive and leaves an empty or corrupted conftest.tar file behind.
    In the next step, pax tries to extract this incomplete or corrupted
    archive and this *** hangs the whole ./configure script ***.

    Note: GNU cpio 2.9 pretends to pass the test but it is a LIE: it
    silently truncates any big UID to its lower 21 bits. I don't know
    what can be the consequences of this lie.

Months later, Petr Hracek <[email-masked]> reports a similar issue
(in bug#13588) for Fedora 17:

    I am trying to solve problem in case a user is created with big
    UID and during configuration pax hangs with message

        ATTENTION! pax archive volume change required.
        Ready for archive volume: 1
        Input archive name or "." to quit pax.
        Archive name >

    and needs user interaction.

    Reference: <https://bugzilla.redhat.com/show_bug.cgi?id=843376>

Time to fix this issue, on the line of a preliminary patch provided by
Petr Hracek in bug#13588.

* m4/tar.m4 (_AM_PROG_TAR): Don't use 'pax' if the UID or GID of the
current user is too high (> 2097151).
* NEWS: Update.
* THANKS: Likewise.

Signed-off-by: Stefano Lattarini <[email-masked]>
---
 NEWS      |  6 ++++++
 THANKS    |  3 +++
 m4/tar.m4 | 26 +++++++++++++++++++++++++-
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/NEWS b/NEWS
index f9a1fb1..863ffdf 100644
--- a/NEWS
+++ b/NEWS
@@ -78,6 +78,12 @@ New in 1.13.2:

 * Bugs fixed:

+  - When the 'ustar' option is used, the generated configure script no
+    longer risks hanging during the tests for the availability of the
+    'pax' utility, even if the user running configure has a UID or GID
+    that requires more than 21 bits to be represented.
+    See automake bug#8343 and bug#13588.
+
   - The obsolete macros AM_CONFIG_HEADER or AM_PROG_CC_STDC work once
     again, as they did in Automake 1.12.x (albeit printing runtime
     warnings in the 'obsolete' category).  Removing them has turned
diff --git a/THANKS b/THANKS
index 66498d4..a574909 100644
--- a/THANKS
+++ b/THANKS
@@ -224,6 +224,7 @@ Luo Yi                          [email-masked]
 Maciej Stachowiak               [email-masked]
 Maciej W. Rozycki               [email-masked]
 Manu Rouat                      [email-masked]
+Marc Herbert                    [email-masked]
 Marcus Brinkmann                [email-masked]
 Marcus G. Daniels               [email-masked]
 Marius Vollmer                  [email-masked]
@@ -311,6 +312,7 @@ Peter Muir                      [email-masked]
 Peter O'Gorman                  [email-masked]
 Peter Rosin                     [email-masked]
 Peter Seiderer                  [email-masked]
+Petr Hracek                     [email-masked]
 Petter Reinholdtsen             [email-masked]
 Petteri Räty                    [email-masked]
 Phil Edwards                    [email-masked]
@@ -391,6 +393,7 @@ Tim Rice                        [email-masked]
 Tim Van Holder                  [email-masked]
 Toshio Kuratomi                 [email-masked]
 Tom Epperly                     [email-masked]
+Tom Rini                        [email-masked]
 Ulrich Drepper                  [email-masked]
 Ulrich Eckhardt                 [email-masked]
 Václav Haisman                  [email-masked]
diff --git a/m4/tar.m4 b/m4/tar.m4
index ec8c83e..61c1206 100644
--- a/m4/tar.m4
+++ b/m4/tar.m4
@@ -81,7 +81,31 @@ do
   AM_RUN_LOG([tardir=conftest.dir && eval $am__tar_ >conftest.tar])
   rm -rf conftest.dir
   if test -s conftest.tar; then
-    AM_RUN_LOG([$am__untar <conftest.tar])
+    m4_if([$1], [ustar], [
+      if test "$_am_tool" = pax; then
+        # Automake bugs #8343 and #13588: 'pax' can hang when UIDs
+        # or GIDs are involved that requires more than 21 bits to
+        # be stored.
+        am_max_uid=2097151 # 2^21 - 1
+        am_max_gid=$am_max_uid
+        # The $UID and $GID variables are not portable, so we need to
+        # resort to the POSIX-mandated id(1) utility.  Errors here are
+        # definitely unexpected, so allow the users to see them (i.e.,
+        # no stderr redirection).
+        am_uid=`id -u || echo unknown`
+        am_gid=`id -g || echo unknown`
+        if test $am_uid -le $am_max_uid; then :; else
+          AS_ECHO(["$as_me:$LINENO: UID '$am_uid' too large for ustar"]) \
+            >&AS_MESSAGE_LOG_FD
+          continue
+        fi
+        if test $am_gid -le $am_max_gid; then :; else
+          AS_ECHO(["$as_me:$LINENO: GID '$am_gid' too large for ustar"]) \
+            >&AS_MESSAGE_LOG_FD
+          continue
+        fi
+      fi
+    ]) # $1 == ustar
     grep GrepMe conftest.dir/file >/dev/null 2>&1 && break
   fi
 done
-- 
1.8.2.1.389.gcaa7d79