[PATCH 3.10 17/44] HID: i2c-hid: fix race condition reading reports

Greg Kroah-Hartman
2015-01-14T07:38:44Z

From: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>

commit 6296f4a8eb86f9abcc370fb7a1a116b8441c17fd upstream.

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: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
[Antonio Borneo: cleanup, rebase to v3.17, submit mainline]
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/hid/i2c-hid/i2c-hid.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -134,6 +134,7 @@ 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 */

@@ -471,9 +472,11 @@ static void i2c_hid_find_max_report(stru
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;
@@ -489,10 +492,11 @@ static int i2c_hid_alloc_buffers(struct
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;
}
@@ -519,12 +523,12 @@ static int i2c_hid_get_raw_report(struct

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;
@@ -533,7 +537,7 @@ static int i2c_hid_get_raw_report(struct

/* 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;
}