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Commit 6296f4a8 authored by Jean-Baptiste Maneyrol's avatar Jean-Baptiste Maneyrol Committed by Jiri Kosina
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HID: i2c-hid: fix race condition reading reports 



Current driver uses a common buffer for reading reports either
synchronously in i2c_hid_get_raw_report() and asynchronously in
the interrupt handler.
There is race condition if an interrupt arrives immediately after
the report is received in i2c_hid_get_raw_report(); the common
buffer is modified by the interrupt handler with the new report
and then i2c_hid_get_raw_report() proceed using wrong data.

Fix it by using a separate buffers for synchronous reports.

Signed-off-by: default avatarJean-Baptiste Maneyrol <jmaneyrol@invensense.com>
[Antonio Borneo: cleanup, rebase to v3.17, submit mainline]
Signed-off-by: default avatarAntonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: default avatarBenjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent 08bb7bea

drivers/hid/i2c-hid/i2c-hid.c

+8 −4
Original line number Diff line number Diff line
@@ -137,6 +137,7 @@ struct i2c_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 */
@@ -504,9 +505,11 @@ static void i2c_hid_find_max_report(struct hid_device *hid, unsigned int type, 
static void i2c_hid_free_buffers(struct i2c_hid *ihid)

{

	kfree(ihid->inbuf);

	kfree(ihid->rawbuf);

	kfree(ihid->argsbuf);

	kfree(ihid->cmdbuf);

	ihid->inbuf = NULL;

	ihid->rawbuf = NULL;

	ihid->cmdbuf = NULL;

	ihid->argsbuf = NULL;

	ihid->bufsize = 0;
@@ -522,10 +525,11 @@ static int i2c_hid_alloc_buffers(struct i2c_hid *ihid, size_t report_size) 
		       report_size; /* report */



	ihid->inbuf = kzalloc(report_size, GFP_KERNEL);

	ihid->rawbuf = kzalloc(report_size, GFP_KERNEL);

	ihid->argsbuf = kzalloc(args_len, GFP_KERNEL);

	ihid->cmdbuf = kzalloc(sizeof(union command) + args_len, GFP_KERNEL);



	if (!ihid->inbuf || !ihid->argsbuf || !ihid->cmdbuf) {

	if (!ihid->inbuf || !ihid->rawbuf || !ihid->argsbuf || !ihid->cmdbuf) {

		i2c_hid_free_buffers(ihid);

		return -ENOMEM;

	}
@@ -552,12 +556,12 @@ static int i2c_hid_get_raw_report(struct hid_device *hid, 


	ret = i2c_hid_get_report(client,

			report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,

			report_number, ihid->inbuf, ask_count);

			report_number, ihid->rawbuf, ask_count);



	if (ret < 0)

		return ret;



	ret_count = ihid->inbuf[0] | (ihid->inbuf[1] << 8);

	ret_count = ihid->rawbuf[0] | (ihid->rawbuf[1] << 8);



	if (ret_count <= 2)

		return 0;
@@ -566,7 +570,7 @@ static int i2c_hid_get_raw_report(struct hid_device *hid, 


	/* The query buffer contains the size, dropping it in the reply */

	count = min(count, ret_count - 2);

	memcpy(buf, ihid->inbuf + 2, count);

	memcpy(buf, ihid->rawbuf + 2, count);



	return count;

}