RFR [XS] : 8175000 : jexec fails to execute simple helloworld.jar

[Baesken, Matthias]

Hello,  probably I should add the info that the fix is needed  in jdk9 as well , not only jdk10 .

Without the fix jdk9/10    show this error  when executing a small  example jar :

/myjdk9/images/jdk/lib/jexec      /java_test/hellojar/helloworld.jar
invalid file (bad magic number): Exec format error

with the fix :

jdk/lib/jexec    /java_test/hellojar/helloworld.jar
Hello world from a jar file


And btw I really wonder  - is  jexec still needed in future jdk's like jdk10  ? Seems it is not used much .

Best regards, Matthias


From: Baesken, Matthias
Sent: Mittwoch, 22. Februar 2017 18:16
To: core-libs-dev at openjdk.java.net
Cc: Langer, Christoph <christoph.langer at sap.com>; Erik Joelsson (erik.joelsson at oracle.com) <erik.joelsson at oracle.com>
Subject: RFR [XS] : 8175000 : jexec fails to execute simple helloworld.jar

Hello , when looking into  the jexec build I noticed   that  execution of a simple helloworld.jar   with jexec does not work any more.

I did a little patch for this which adjusted the addition done with  CR  8156478: 3 Buffer overrun defect groups in jexec.c<https://javapartner.oracle.com/mproxy/repository/technology/java2/jdk9/jdk/rev/4f96129b45ee>  .

Could I have a review ( just a diff this time is provided because of infrastructure issues) for it ?


Thanks, Matthias

Bug :
https://bugs.openjdk.java.net/browse/JDK-8175000


Diff for jdk10  :

# HG changeset patch
# User mbaesken
# Date 1487782485 -3600
#      Wed Feb 22 17:54:45 2017 +0100
# Node ID 93d55a711f3b1c3f282e6889c24d13f16d4a4548
# Parent  884872263accabd4ab68d005abd4e5393144aa4f
8175000: jexec fails to execute simple helloworld.jar

diff --git a/src/java.base/unix/native/launcher/jexec.c b/src/java.base/unix/native/launcher/jexec.c
--- a/src/java.base/unix/native/launcher/jexec.c
+++ b/src/java.base/unix/native/launcher/jexec.c
@@ -331,8 +331,9 @@
                 off_t end   = start  + xlen;

                 if (end <= count) {
-                    end -= 4; // make sure there are 4 bytes to read at start
-                    while (start < end) {
+                    // make sure there are 4 bytes to read at start
+                    end -= 3;
+                    while ((start < end) && (start < count-3)) {
                         off_t xhid  = SH(buf, start);
                         off_t xdlen = SH(buf, start + 2);