releases/3.10.61/dell-wmi-fix-access-out-of-memory.patch

From a666b6ffbc9b6705a3ced704f52c3fe9ea8bf959 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@gmail.com>
Date: Mon, 29 Sep 2014 15:10:51 +0200
Subject: dell-wmi: Fix access out of memory
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From: =?UTF-8?q?Pali=20Roh=C3=A1r?= <pali.rohar@gmail.com>

commit a666b6ffbc9b6705a3ced704f52c3fe9ea8bf959 upstream.

Without this patch, dell-wmi is trying to access elements of dynamically
allocated array without checking the array size. This can lead to memory
corruption or a kernel panic. This patch adds the missing checks for
array size.

Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/platform/x86/dell-wmi.c |   12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

--- a/drivers/platform/x86/dell-wmi.c
+++ b/drivers/platform/x86/dell-wmi.c
@@ -163,18 +163,24 @@ static void dell_wmi_notify(u32 value, v
 		const struct key_entry *key;
 		int reported_key;
 		u16 *buffer_entry = (u16 *)obj->buffer.pointer;
+		int buffer_size = obj->buffer.length/2;
 
-		if (dell_new_hk_type && (buffer_entry[1] != 0x10)) {
+		if (buffer_size >= 2 && dell_new_hk_type && buffer_entry[1] != 0x10) {
 			pr_info("Received unknown WMI event (0x%x)\n",
 				buffer_entry[1]);
 			kfree(obj);
 			return;
 		}
 
-		if (dell_new_hk_type || buffer_entry[1] == 0x0)
+		if (buffer_size >= 3 && (dell_new_hk_type || buffer_entry[1] == 0x0))
 			reported_key = (int)buffer_entry[2];
-		else
+		else if (buffer_size >= 2)
 			reported_key = (int)buffer_entry[1] & 0xffff;
+		else {
+			pr_info("Received unknown WMI event\n");
+			kfree(obj);
+			return;
+		}
 
 		key = sparse_keymap_entry_from_scancode(dell_wmi_input_dev,
 							reported_key);