[3.16.y-ckt stable] Patch "ath9k: fix buffer overrun for ar9287" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ath9k: fix buffer overrun for ar9287

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt27.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From 4d33c479e0f61862e81b7579c3f563af5a9aa37e Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd at arndb.de>
Date: Mon, 14 Mar 2016 15:18:36 +0100
Subject: ath9k: fix buffer overrun for ar9287

commit 83d6f1f15f8cce844b0a131cbc63e444620e48b5 upstream.

Code that was added back in 2.6.38 has an obvious overflow
when accessing a static array, and at the time it was added
only a code comment was put in front of it as a reminder
to have it reviewed properly.

This has not happened, but gcc-6 now points to the specific
overflow:

drivers/net/wireless/ath/ath9k/eeprom.c: In function 'ath9k_hw_get_gain_boundaries_pdadcs':
drivers/net/wireless/ath/ath9k/eeprom.c:483:44: error: array subscript is above array bounds [-Werror=array-bounds]
     maxPwrT4[i] = data_9287[idxL].pwrPdg[i][4];
                   ~~~~~~~~~~~~~~~~~~~~~~~~~^~~

It turns out that the correct array length exists in the local
'intercepts' variable of this function, so we can just use that
instead of hardcoding '4', so this patch changes all three
instances to use that variable. The other two instances were
already correct, but it's more consistent this way.

Signed-off-by: Arnd Bergmann <arnd at arndb.de>
Fixes: 940cd2c12ebf ("ath9k_hw: merge the ar9287 version of ath9k_hw_get_gain_boundaries_pdadcs")
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/wireless/ath/ath9k/eeprom.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/eeprom.c b/drivers/net/wireless/ath/ath9k/eeprom.c
index 971d770722cf..2ac05486424b 100644
--- a/drivers/net/wireless/ath/ath9k/eeprom.c
+++ b/drivers/net/wireless/ath/ath9k/eeprom.c
@@ -408,10 +408,9 @@ void ath9k_hw_get_gain_boundaries_pdadcs(struct ath_hw *ah,

 	if (match) {
 		if (AR_SREV_9287(ah)) {
-			/* FIXME: array overrun? */
 			for (i = 0; i < numXpdGains; i++) {
 				minPwrT4[i] = data_9287[idxL].pwrPdg[i][0];
-				maxPwrT4[i] = data_9287[idxL].pwrPdg[i][4];
+				maxPwrT4[i] = data_9287[idxL].pwrPdg[i][intercepts - 1];
 				ath9k_hw_fill_vpd_table(minPwrT4[i], maxPwrT4[i],
 						data_9287[idxL].pwrPdg[i],
 						data_9287[idxL].vpdPdg[i],
@@ -421,7 +420,7 @@ void ath9k_hw_get_gain_boundaries_pdadcs(struct ath_hw *ah,
 		} else if (eeprom_4k) {
 			for (i = 0; i < numXpdGains; i++) {
 				minPwrT4[i] = data_4k[idxL].pwrPdg[i][0];
-				maxPwrT4[i] = data_4k[idxL].pwrPdg[i][4];
+				maxPwrT4[i] = data_4k[idxL].pwrPdg[i][intercepts - 1];
 				ath9k_hw_fill_vpd_table(minPwrT4[i], maxPwrT4[i],
 						data_4k[idxL].pwrPdg[i],
 						data_4k[idxL].vpdPdg[i],
@@ -431,7 +430,7 @@ void ath9k_hw_get_gain_boundaries_pdadcs(struct ath_hw *ah,
 		} else {
 			for (i = 0; i < numXpdGains; i++) {
 				minPwrT4[i] = data_def[idxL].pwrPdg[i][0];
-				maxPwrT4[i] = data_def[idxL].pwrPdg[i][4];
+				maxPwrT4[i] = data_def[idxL].pwrPdg[i][intercepts - 1];
 				ath9k_hw_fill_vpd_table(minPwrT4[i], maxPwrT4[i],
 						data_def[idxL].pwrPdg[i],
 						data_def[idxL].vpdPdg[i],