On 22/03/2018 2:41 AM, Alex Menkov wrote:
Hi David,
On 03/20/2018 21:51, David Holmes wrote:
Hi Alex,
On 21/03/2018 3:25 AM, Alex Menkov wrote:
Hi David,
On 03/19/2018 18:10, David Holmes wrote:
Hi Alex,
On 20/03/2018 10:28 AM, Alex Menkov wrote:
Hi guys,
please re-review the fix.
I still have an unanswered question about where the max of 49 is
enforced. I see it for the "address" but not names in general. ??
for shmem the "channel name" is the address (it's checked in
createTransport/openTransport).
Names for mutexes/events are generated by appending some strings to
the adddress and length of the added parts are supposed to be less
than MAX_IPC_SUFFIX (25 symbols):
".mutex" (+ up to 3 symbols)
".hasData" (+ up to 3 symbols)
".hasSpace" (+ up to 3 symbols)
".ctos"
".stoc"
".accept" (+ up to 3 symbols)
".attach" (+ up to 3 symbols)
".<pid>" (pid is a DWORD)
Okay so ... the code in shmemBase.c is very unclear as to which
"names" can come in from an external source and which are only ever
derived from other "names". If the "address" (which seems a very bad
description in this case!) is the only external source for a name, and
it is limited to a length of 49 then that is okay.
Yes, the "address" is the only external arg, all other names are
constructed from it.
I believe it's "address" because it comes from "address" parameter:
-Xrunjdwp:transport=st_shmem,address=<shmem_name>
Reg.test is added the the issue.
I don't quite follow the test. I see you try to set the name with a
value that is too long, and if that doesn't cause an overflow and we
don't crash that is good. But I'd expect you to read back the name
and check it matches the truncated name with 49 characters.
The test specifies the maximum length supported (49 symbols)
(if longer name is specified, "address strings longer than 50
characters are invalid" error reported).
I missed the substring that simply causes the name to be the maximum
supported length. That would trigger the overflow and so suffices as a
regression test for this fix.
Is there another test that already passes a too-long name and verifies
the error gets thrown?
Do you mean name >= 50 symbols?
No, there is no such test.
I don't think it make much sense (test an arbitrary
implementation-specific restriction), but I can add the case to the test.
It ensures that using a too-long name fails gracefully.
Thanks,
David
--alex
As far as I see there is no way to read back the name used to create
the transport.
Ok.
Thanks,
David
-----
--alex
Thanks,
David
webrev:
http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open.04/
--alex
On 03/13/2018 16:14, Alex Menkov wrote:
Hi all,
Please review a small fix for
https://bugs.openjdk.java.net/browse/JDK-8049695
webrev:
http://cr.openjdk.java.net/~amenkov/shmem_long_name/webrev_open/
Root cause of the issue is jbd hungs as a result of the buffer
overflow.
In the beginning of the shmemBase.c:
#define MAX_IPC_PREFIX 50 /* user-specified or generated name
for */
/* shared memory seg and prefix for
other IPC */
#define MAX_IPC_SUFFIX 25 /* suffix to shmem name for other IPC
names */
#define MAX_IPC_NAME (MAX_IPC_PREFIX + MAX_IPC_SUFFIX)
buffer (char prefix[]) in function createStream is used to
generate base name for mutex/events, so MAX_IPC_PREFIX is not big
enough.
--alex
