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Subject[PATCH 3.16.y-ckt 254/254] dell-wmi: Fix access out of memory
Date
3.16.7-ckt2 -stable review patch.  If anyone has any objections, please let me know.

------------------

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: Luis Henriques <luis.henriques@canonical.com>
---
drivers/platform/x86/dell-wmi.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c
index 390e8e33d5e3..25721bf20092 100644
--- 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, void *context)
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);
--
2.1.0
--
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