Patch "xen/pciback: Fix conf_space read/write overlap check." has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

xen/pciback: Fix conf_space read/write overlap check.

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xen-pciback-fix-conf_space-read-write-overlap-check.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Andrey Grodzovsky <[email protected]>
Date: Tue, 21 Jun 2016 14:26:36 -0400
Subject: xen/pciback: Fix conf_space read/write overlap check.

From: Andrey Grodzovsky <[email protected]>

commit 02ef871ecac290919ea0c783d05da7eedeffc10e upstream.

Current overlap check is evaluating to false a case where a filter field is fully contained (proper subset) of a r/w request. This change applies classical overlap check instead to include all the scenarios.

More specifically, for (Hilscher GmbH CIFX 50E-DP(M/S)) device driver the logic is such that the entire confspace is read and written in 4 byte chunks. In this case as an example, CACHE_LINE_SIZE, LATENCY_TIMER and PCI_BIST are arriving together in one call to xen_pcibk_config_write() with offset == 0xc and size == 4. With the exsisting overlap check the LATENCY_TIMER field (offset == 0xd, length == 1) is fully contained in the write request and hence is excluded from write, which is incorrect.

---
 drivers/xen/xen-pciback/conf_space.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

@@ -183,8 +183,7 @@ int xen_pcibk_config_read(struct pci_dev
 		field_start = OFFSET(cfg_entry);
 		field_end = OFFSET(cfg_entry) + field->size;
 
-		if ((req_start >= field_start && req_start < field_end)
-		    || (req_end > field_start && req_end <= field_end)) {
+		 if (req_end > field_start && field_end > req_start) {
 			err = conf_space_read(dev, cfg_entry, field_start,
 					      &tmp_val);
 			if (err)

@@ -230,8 +229,7 @@ int xen_pcibk_config_write(struct pci_de
 		field_start = OFFSET(cfg_entry);
 		field_end = OFFSET(cfg_entry) + field->size;
 
-		if ((req_start >= field_start && req_start < field_end)
-		    || (req_end > field_start && req_end <= field_end)) {
+		 if (req_end > field_start && field_end > req_start) {
 			tmp_val = 0;
 
 			err = xen_pcibk_config_read(dev, field_start,

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/xen-pciback-fix-conf_space-read-write-overlap-check.patch