s390/pci: fix out of bounds access during irq setup

[bugproxy]

== SRU Justification ==

IBM is requesting this commit (from 4.19) for s390: 866f3576a72b2233a76dffb80290f8086dc49e17
It fixes a problem with requesting more interrupts than supported on s390.
The issue can finally lead to an out of bounds access.

It needs to be applied to 18.04 and 16.04 (in addition to cosmic).

== Fix ==

commit 866f3576a72b2233a76dffb80290f8086dc49e17 upstream.

During interrupt setup we allocate interrupt vectors, walk the list of msi
descriptors, and fill in the message data. Requesting more interrupts than
supported on s390 can lead to an out of bounds access.

When we restrict the number of interrupts we should also stop walking the
msi list after all supported interrupts are handled.

== Regression Potential ==

Low. The modification is limited to the following two lines in s390/pci:
...
+ if (hwirq >= msi_vecs)
+ break;
...

https://lkml.org/lkml/2018/9/3/1125

== Test Case ==

A test case will be provided by IBM.
And the test and verification will also be done by IBM.

__________

Bug Description:

s390/pci: fix out of bounds access during irq setup

During interrupt setup we allocate interrupt vectors, walk the list of msi
descriptors, and fill in the message data. Requesting more interrupts than
supported on s390 can lead to an out of bounds access.

When we restrict the number of interrupts we should also stop walking the
msi list after all supported interrupts are handled.

Upstream-ID: 866f3576a72b2233a76dffb80290f8086dc49e17
kernel 4.19

Also to be applied to 18.10

[Ubuntu Foundations Team Bug Bot (crichton)]

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[Dimitri John Ledkov (xnox)]

Staged for cosmic, in master-next.

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-09-05 04:30 EDT-------
just to clarify it needs to be integrated into 18.10 and SRUed to 18.04

------- Comment From <email address hidden> 2018-09-05 10:44 EDT-------
this bugzilla is a duplicate of https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1790480 . Please close it........

[Frank Heimes (fheimes)]

Since this is a duplicate, so please see LP 1790480
It landed in cosmic, bionic and xenial.

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-10-18 04:42 EDT-------
@Canonical: any progress here? Many thx in advance

[bugproxy (bugproxy)]

------- Comment From <email address hidden> 2018-10-18 05:10 EDT-------
*** This bug has been marked as a duplicate of bug 170595 ***

------- Comment From <email address hidden> 2018-10-18 05:11 EDT-------
IBM Bugzilla status-> closed,