HID: core: Correctly handle ReportSize being zero
commit bce1305c0ece3dc549663605e567655dd701752c upstream.
It appears that a ReportSize value of zero is legal, even if a bit
non-sensical. Most of the HID code seems to handle that gracefully,
except when computing the total size in bytes. When fed as input to
memset, this leads to some funky outcomes.
Detect the corner case and correctly compute the size.
Cc: stable@vger.kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit cf7797ea60e3e721e3ae5090edbc2ec72d715436)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 4f3706e..b49211c 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1407,6 +1407,17 @@
}
/*
+ * Compute the size of a report.
+ */
+static size_t hid_compute_report_size(struct hid_report *report)
+{
+ if (report->size)
+ return ((report->size - 1) >> 3) + 1;
+
+ return 0;
+}
+
+/*
* Create a report. 'data' has to be allocated using
* hid_alloc_report_buf() so that it has proper size.
*/
@@ -1418,7 +1429,7 @@
if (report->id > 0)
*data++ = report->id;
- memset(data, 0, ((report->size - 1) >> 3) + 1);
+ memset(data, 0, hid_compute_report_size(report));
for (n = 0; n < report->maxfield; n++)
hid_output_field(report->device, report->field[n], data);
}
@@ -1545,7 +1556,7 @@
csize--;
}
- rsize = ((report->size - 1) >> 3) + 1;
+ rsize = hid_compute_report_size(report);
if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE)
rsize = HID_MAX_BUFFER_SIZE - 1;