[1/2] HID: core: i2c-hid: fix size check and type usage

BugLink: https://bugs.launchpad.net/bugs/1741168

Link: https://patchwork.kernel.org/patch/10141099/

When convert char array with signed int, if the inbuf[x] is negative then
upper bits will be set to 1. Fix this by using u8 instead of char.

ret_size has to be at least 3, hid_input_report use it after minus 2 bytes.

size should be more than 0 to keep memset safe.

Cc: stable@vger.kernel.org
Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
---
 drivers/hid/hid-core.c        |  4 ++--
 drivers/hid/i2c-hid/i2c-hid.c | 10 +++++-----
 2 files changed, 7 insertions(+), 7 deletions(-)

> On 4 Jan 2018, at 2:06 PM, Aaron Ma <aaron.ma@canonical.com> wrote:
> 
> BugLink: https://bugs.launchpad.net/bugs/1741168
> 
> Link: https://patchwork.kernel.org/patch/10141099/
> 
> When convert char array with signed int, if the inbuf[x] is negative then
> upper bits will be set to 1. Fix this by using u8 instead of char.
> 
> ret_size has to be at least 3, hid_input_report use it after minus 2 bytes.
> 
> size should be more than 0 to keep memset safe.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
> ---
> drivers/hid/hid-core.c        |  4 ++--
> drivers/hid/i2c-hid/i2c-hid.c | 10 +++++-----
> 2 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index efb3501b4123..c40dc6406966 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -1506,7 +1506,7 @@ int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, int size,
> 	if (rsize > HID_MAX_BUFFER_SIZE)
> 		rsize = HID_MAX_BUFFER_SIZE;
> 
> -	if (csize < rsize) {
> +	if ((csize < rsize) && (csize > 0)) {
> 		dbg_hid("report %d is too short, (%d < %d)\n", report->id,
> 				csize, rsize);
> 		memset(cdata + csize, 0, rsize - csize);

Why is skipping memset() when csize == 0 necessary?

Kai-Heng

> @@ -1566,7 +1566,7 @@ int hid_input_report(struct hid_device *hid, int type, u8 *data, int size, int i
> 	report_enum = hid->report_enum + type;
> 	hdrv = hid->driver;
> 
> -	if (!size) {
> +	if (size <= 0) {
> 		dbg_hid("empty report\n");
> 		ret = -1;
> 		goto unlock;
> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> index 364150435c62..4b3a703f297b 100644
> --- a/drivers/hid/i2c-hid/i2c-hid.c
> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> @@ -143,10 +143,10 @@ struct i2c_hid {
> 						   * register of the HID
> 						   * descriptor. */
> 	unsigned int		bufsize;	/* i2c buffer size */
> -	char			*inbuf;		/* Input buffer */
> -	char			*rawbuf;	/* Raw Input buffer */
> -	char			*cmdbuf;	/* Command buffer */
> -	char			*argsbuf;	/* Command arguments buffer */
> +	u8			*inbuf;		/* Input buffer */
> +	u8			*rawbuf;	/* Raw Input buffer */
> +	u8			*cmdbuf;	/* Command buffer */
> +	u8			*argsbuf;	/* Command arguments buffer */
> 
> 	unsigned long		flags;		/* device flags */
> 	unsigned long		quirks;		/* Various quirks */
> @@ -468,7 +468,7 @@ static void i2c_hid_get_input(struct i2c_hid *ihid)
> 
> 	ret_size = ihid->inbuf[0] | ihid->inbuf[1] << 8;
> 
> -	if (!ret_size) {
> +	if (ret_size <= 2) {
> 		/* host or device initiated RESET completed */
> 		if (test_and_clear_bit(I2C_HID_RESET_PENDING, &ihid->flags))
> 			wake_up(&ihid->wait);
> -- 
> 2.14.3
> 
> 
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