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Introduction
We would like to advise you of a set of
situations that Hewlett-Packard has
identified with MPE/iX software which, in
very rare circumstances, could lead to data
corruption on HP e3000 systems running
MPE/iX Releases 6.5, 7.0, and 7.5.
Hewlett-Packard has software patches for
these releases ready to correct these
situations, MPENX11 and MILNX10, available
at the
HP ITRC or via your HP Support
Representative. Though Hewlett-Packard
believes very few, if any, customers are at
risk, HP strongly recommends that all
customers take the following corrective
actions:
- Install MPENX11 and MILNX10 at your
earliest possible convenience (see the patch
descriptions below)
- Your non-HP applications may be
impacted: examine the applications running
on your systems to determine if they meet
the criteria to require a recompile (see the
notes on patch MILNX10 below).
November 2nd, 2007 Update: FAQ now
available
here.
Patch
Information
Patch MPENX11 addresses the following issues
with MPE/iX: |
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- SORT.PUB.SYS and programmatic calls to
HPSORTOUTPUT: Customers on MPE/iX Release
6.5, 7.0 or 7.5 who sort 4GB or more of data are
at risk. When either interface is used to sort
more than 4GB of data, the returned record
length could in rare instances be corrupted. If
the record length returned is less than it
should be then data could be lost.
- MPE/iX OS millicode handling of long
pointer access to large files: When the OS
copies data from a long pointer location only
one byte from a range is moved if, and only if
that range starts six, five, four, three or two
bytes from the end of a four gigabyte space and
the length of the move transfers all remaining
bytes of the space. No other source address or
transfer length combinations are affected nor
are transfers to such addresses. See the
section
What is the issue for more information.
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Patch MILNX10 addresses potential issues with
non-HP Software: |
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It is possible for non-HP Software to have an
issue similar to the MPE/iX OS millicode issue
described above and thus be at risk of
corrupting data. Addressing this issue may
require that non-HP Software be recompiled after
installation of MILNX10.
Recompilation is not required for programs
reading data exclusively through MPE/iX File
System intrinsics like FREAD, FREADDIR or HP
compiler library file access routines such as
C/iX read(), Pascal/iX read(), COBOL READ, as
long as patch MPENX11 is installed. A recompile
may be required if customers and ISVs have
written code to read data from files four
gigabytes and larger using
Large Mapped pointers, AND used move_fast or
code statements that result in a call to
$$lr_unk_unk_long or $$lr_na_unk_long. Then, as
in the OS issue above, if data is moved starting
at locations six or fewer bytes from the end of
a four gigabyte boundary, millicode could
silently move less than the requested amount of
data. HP recommends that customers and ISVs
rebuild any applications which read data from
large files via long pointers to include the new
version of the $$lr_unk_unk_long and
$$lr_na_unk_long routines via the new
MILLI.LIB.SYS delivered in MILNX10.
Additional information about these issues can be found in the following
sections.
The impacted code involves the “millicode”
routines $$lr_unk_unk_long, which implement the
PASCAL predefined function “move_fast” and
$$lr_na_unk_long. These millicode routines
are also used by HP's Pascal and C compilers to
implement data movement operations for addresses
referenced by
Long Pointers. The following table describes
the five combinations of long pointer source
address and move length that exhibit the issue.
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Source value (in hex) |
Length value |
Destination Alignment |
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$SID.fffffffa |
6 |
any |
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$SID.fffffffb |
5 |
any |
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$SID.fffffffc |
4 |
non-word aligned |
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$SID.fffffffd |
3 |
any |
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$SID.fffffffe |
2 |
any |
When these combinations of parameters are
passed, the impacted version of the millicode
will move only one byte of the range. No
other source address, destination address, or
transfer length combinations are affected.
Software Supplied by HP
Patch MPENX11 addresses these issues for all HP
e3000 FOS and SUBSYS software.
Software written for your own use
The good news for your own applications is that
with MPENX11 programs which simply call FREAD,
FREADDIR or use a language's specific equivalent
functions like COBOL READ, Pascal/iX read() and
C/iX read() are not exposed to this issue.
To be at risk a programmer must have taken some
very specific actions. These are:
1) You must open
Large Files -- If you don't use MPE
Files which are capable of containing more than
4GB minus 64KB of data then you won't have a
issue. See
Looking for
Large Files on your system for more
information.
2) You must be using long pointers to access
data in a file 4GB minus 64KB or larger. To use
a long pointer in a user mode application, it
must have been written in C/iX or Pascal/iX AND
have called HPFOPEN with a unique itemnum.
Details:
a) The only HP supplied compilers which support long pointers are Pascal/iX
and C/iX. Programs written in other HP languages such as COBOL
and Fortran cannot directly create or access long pointers. See
Looking for Long Pointers in Program Source section for additional
information in recognizing long pointers in your code.
b) To obtain a long pointer to a large file, user mode
code must call HPFOPEN using itemnum 87, the "Large Mapped Access" option.
Please refer to the MPE/iX Intrinsics manual at:
http://docs.hp.com/en/32650-90905/ch07s29.html for more information
about Large Mapped Access.
3) You must then move data in these files using
Pascal/iX move_fast() or your own byte copy
routines which result in calls to
$$lr_unk_unk_long or $$lr_na_unk_long in
conjunction with the five address & length
combinations shown above in "What
is the issue?". Calls to other
Pascal/iX "move" functions or to HP intrinsics
such as HPFMOVEDATA, HPFMOVEDATALTOR or
HPFMOVEDATARTOL are all safe as long as you've
installed MPENX11.
Regardless of the current state of your
applications HP recommends that all customers
install MPENX11 and MILNX10.
The following sections provide further details to assist customers and ISVs
in assessing their software's susceptibility to these issues.
Large Files are
defined as files built with a file limit
allowing more than 4GB minus 64KB of data to be
stored. In assessing your risk we advise
you to take the following steps.
1) You can look for Large Files that are currently on your system in a number
of ways. See
http://docs.hp.com/en/30216-90291/ch03s01.html
for details about changes to HP intrinsics which allow programmers to gather
information about Large Files. HP has written a tool called FILECHEK that
will look at all PERMANENT files on your system and determine if they are
susceptible to the issues.
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CAUTION: Simply running this tool is not
sufficient to determine if your applications and files are susceptible to
this issue. This tool can only detect files currently on your system
which exist in the MPE/iX PERMANENT domain. This program does not
detect files built in a JOB or SESSION's TEMPORARY domain. |
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For more information on FILECHEK click
here.
2) You should monitor your system for Large Files usage including those built
for temporary use by turning on MPE/iX System Logging type 105 (NM File Close)
records. Type 305 records will be created whenever any Large File is closed.
Type 105 and type 205 records will also be generated but can be ignored as they
do not indicate the presence of a Large File. See Chapter 6 of the "System
Startup, Configuration, and Shutdown Reference Manual"
http://docs.hp.com/en/32650-90907/ch06.html
for more information about MPE/iX System Logging.
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CAUTION: Enabling the logging of NM File Close
records may cause System Log files to be filled and created at a faster than
normal rate -- care should be taken that adequate disk space is maintained
on LDEV 1 or serious issues can result. |
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If you do find large files or see type 305 records in your system logs you
will need to determine the applications which
are using these files and investigate their
susceptibility these issues; see
"Looking for Long Pointers in Program Source"
for information on evaluating your application
code. Remember patch MPENX11 addresses
these issues for all HP e3000 FOS and SUBSYS
software.
You should scan the source code of your
applications for possible long pointer usage to
determine your susceptibility to these issues.
The only HP supplied compilers which allow "long
pointer" usage are C/iX and Pascal/iX. COBOL,
Fortran and other HP supplied languages do
not allow long pointer usage; programs and
library functions written in those languages
require no direct changes. To obtain a long
pointer to a large file, user mode code must
call HPFOPEN using itemnum 87, the "Large Mapped
Access" option. HP recommends that
any application written in C/iX or Pascal/iX
making a call to HPFOPEN with itemnum 87 be
recompiled and relinked after the installation
of MILNX10 in order to ensure the new millicode
routines are used.
Here are two code fragments which illustrate how a long pointer obtained from
HPFOPEN itemnum 87 might be declared in C/iX and Pascal/iX:
C/iX
/* long pointers are declared with "^" rather than "*" */
char ^long_file_data_ptr;
Pascal/iX
. . .
{ long pointers are declared with $extaddr$ compiler directive }
long_file_data_ptr : ^ $extaddr$ array [1..recsize] of char;
{ globalanyptr type is a long pointer }
global_file_data_ptr : globalanyptr;
{ anyptr type is a long pointer, could have an issue later }
any_file_data_ptr : anyptr;
Remember that simply having a long pointer declared does
not automatically mean you are susceptible to these issues. These
pointers must be used to move data from a large file via calls to move_fast() or
other compiler statement which resolve to $$lr_unk_unk_long or $lr_na_unk_long
order to be susceptible.
In summary, patches MPENX11 and MILNX10 address these issues for all HP e3000
FOS and SUBSYS software. In house applications developed in C/iX or Pascal/iX
will require addition analysis to determine if they should be recompiled (as
described above in "What to look for").
Questions about other applications should be directed to the software support
provider for that application. If you have questions or require help, please
contact your local HP support representative or sales office.
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