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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Will McVicker <willmcvicker@google.com>,
        Jiri Kosina <jkosina@suse.cz>
Subject: [PATCH 5.10 02/23] HID: make arrays usage and value to be the same
Date:   Thu, 25 Feb 2021 10:53:33 +0100
Message-Id: <20210225092516.653936201@linuxfoundation.org>
In-Reply-To: <20210225092516.531932232@linuxfoundation.org>
References: <20210225092516.531932232@linuxfoundation.org>
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From: Will McVicker <willmcvicker@google.com>

commit ed9be64eefe26d7d8b0b5b9fa3ffdf425d87a01f upstream.

The HID subsystem allows an "HID report field" to have a different
number of "values" and "usages" when it is allocated. When a field
struct is created, the size of the usage array is guaranteed to be at
least as large as the values array, but it may be larger. This leads to
a potential out-of-bounds write in
__hidinput_change_resolution_multipliers() and an out-of-bounds read in
hidinput_count_leds().

To fix this, let's make sure that both the usage and value arrays are
the same size.

Cc: stable@vger.kernel.org
Signed-off-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/hid/hid-core.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -90,7 +90,7 @@ EXPORT_SYMBOL_GPL(hid_register_report);
  * Register a new field for this report.
  */
 
-static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages, unsigned values)
+static struct hid_field *hid_register_field(struct hid_report *report, unsigned usages)
 {
 	struct hid_field *field;
 
@@ -101,7 +101,7 @@ static struct hid_field *hid_register_fi
 
 	field = kzalloc((sizeof(struct hid_field) +
 			 usages * sizeof(struct hid_usage) +
-			 values * sizeof(unsigned)), GFP_KERNEL);
+			 usages * sizeof(unsigned)), GFP_KERNEL);
 	if (!field)
 		return NULL;
 
@@ -300,7 +300,7 @@ static int hid_add_field(struct hid_pars
 	usages = max_t(unsigned, parser->local.usage_index,
 				 parser->global.report_count);
 
-	field = hid_register_field(report, usages, parser->global.report_count);
+	field = hid_register_field(report, usages);
 	if (!field)
 		return 0;