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authorLee Jones <lee@kernel.org>2023-01-23 12:39:11 +0000
committerJiri Kosina <jkosina@suse.cz>2023-02-23 11:51:56 +0100
commitb1a37ed00d7908a991c1d0f18a8cba3c2aa99bdc (patch)
tree4ec509588d2eaa3a495286af213ef4bcc3ce2991
parent6c71297eaf713ece684a367ce9aff06069d715b9 (diff)
HID: core: Provide new max_buffer_size attribute to over-ride the default
Presently, when a report is processed, its proposed size, provided by the user of the API (as Report Size * Report Count) is compared against the subsystem default HID_MAX_BUFFER_SIZE (16k). However, some low-level HID drivers allocate a reduced amount of memory to their buffers (e.g. UHID only allocates UHID_DATA_MAX (4k) buffers), rending this check inadequate in some cases. In these circumstances, if the received report ends up being smaller than the proposed report size, the remainder of the buffer is zeroed. That is, the space between sizeof(csize) (size of the current report) and the rsize (size proposed i.e. Report Size * Report Count), which can be handled up to HID_MAX_BUFFER_SIZE (16k). Meaning that memset() shoots straight past the end of the buffer boundary and starts zeroing out in-use values, often resulting in calamity. This patch introduces a new variable into 'struct hid_ll_driver' where individual low-level drivers can over-ride the default maximum value of HID_MAX_BUFFER_SIZE (16k) with something more sympathetic to the interface. Signed-off-by: Lee Jones <lee@kernel.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
-rw-r--r--drivers/hid/hid-core.c32
-rw-r--r--include/linux/hid.h3
2 files changed, 28 insertions, 7 deletions
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 1ee623c26c49..7647a946340c 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -256,6 +256,7 @@ static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsign
{
struct hid_report *report;
struct hid_field *field;
+ unsigned int max_buffer_size = HID_MAX_BUFFER_SIZE;
unsigned int usages;
unsigned int offset;
unsigned int i;
@@ -286,8 +287,11 @@ static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsign
offset = report->size;
report->size += parser->global.report_size * parser->global.report_count;
+ if (parser->device->ll_driver->max_buffer_size)
+ max_buffer_size = parser->device->ll_driver->max_buffer_size;
+
/* Total size check: Allow for possible report index byte */
- if (report->size > (HID_MAX_BUFFER_SIZE - 1) << 3) {
+ if (report->size > (max_buffer_size - 1) << 3) {
hid_err(parser->device, "report is too long\n");
return -1;
}
@@ -1963,6 +1967,7 @@ int hid_report_raw_event(struct hid_device *hid, enum hid_report_type type, u8 *
struct hid_report_enum *report_enum = hid->report_enum + type;
struct hid_report *report;
struct hid_driver *hdrv;
+ int max_buffer_size = HID_MAX_BUFFER_SIZE;
u32 rsize, csize = size;
u8 *cdata = data;
int ret = 0;
@@ -1978,10 +1983,13 @@ int hid_report_raw_event(struct hid_device *hid, enum hid_report_type type, u8 *
rsize = hid_compute_report_size(report);
- if (report_enum->numbered && rsize >= HID_MAX_BUFFER_SIZE)
- rsize = HID_MAX_BUFFER_SIZE - 1;
- else if (rsize > HID_MAX_BUFFER_SIZE)
- rsize = HID_MAX_BUFFER_SIZE;
+ if (hid->ll_driver->max_buffer_size)
+ max_buffer_size = hid->ll_driver->max_buffer_size;
+
+ if (report_enum->numbered && rsize >= max_buffer_size)
+ rsize = max_buffer_size - 1;
+ else if (rsize > max_buffer_size)
+ rsize = max_buffer_size;
if (csize < rsize) {
dbg_hid("report %d is too short, (%d < %d)\n", report->id,
@@ -2396,7 +2404,12 @@ int hid_hw_raw_request(struct hid_device *hdev,
unsigned char reportnum, __u8 *buf,
size_t len, enum hid_report_type rtype, enum hid_class_request reqtype)
{
- if (len < 1 || len > HID_MAX_BUFFER_SIZE || !buf)
+ unsigned int max_buffer_size = HID_MAX_BUFFER_SIZE;
+
+ if (hdev->ll_driver->max_buffer_size)
+ max_buffer_size = hdev->ll_driver->max_buffer_size;
+
+ if (len < 1 || len > max_buffer_size || !buf)
return -EINVAL;
return hdev->ll_driver->raw_request(hdev, reportnum, buf, len,
@@ -2415,7 +2428,12 @@ EXPORT_SYMBOL_GPL(hid_hw_raw_request);
*/
int hid_hw_output_report(struct hid_device *hdev, __u8 *buf, size_t len)
{
- if (len < 1 || len > HID_MAX_BUFFER_SIZE || !buf)
+ unsigned int max_buffer_size = HID_MAX_BUFFER_SIZE;
+
+ if (hdev->ll_driver->max_buffer_size)
+ max_buffer_size = hdev->ll_driver->max_buffer_size;
+
+ if (len < 1 || len > max_buffer_size || !buf)
return -EINVAL;
if (hdev->ll_driver->output_report)
diff --git a/include/linux/hid.h b/include/linux/hid.h
index eaf8ab177303..1ea8c7a3570b 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -834,6 +834,7 @@ struct hid_driver {
* @output_report: send output report to device
* @idle: send idle request to device
* @may_wakeup: return if device may act as a wakeup source during system-suspend
+ * @max_buffer_size: over-ride maximum data buffer size (default: HID_MAX_BUFFER_SIZE)
*/
struct hid_ll_driver {
int (*start)(struct hid_device *hdev);
@@ -859,6 +860,8 @@ struct hid_ll_driver {
int (*idle)(struct hid_device *hdev, int report, int idle, int reqtype);
bool (*may_wakeup)(struct hid_device *hdev);
+
+ unsigned int max_buffer_size;
};
extern bool hid_is_usb(const struct hid_device *hdev);