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Subject[PATCH v2 08/31] dib0700_core: don't use stack on I2C reads
Date
Be sure that I2C reads won't use stack by passing
a pointer to the state buffer, that we know it was
allocated via kmalloc, instead of relying on the buffer
allocated by an I2C client.

Reviewed-By: Patrick Boettcher <patrick.boettcher@posteo.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
drivers/media/usb/dvb-usb/dib0700_core.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/dvb-usb/dib0700_core.c b/drivers/media/usb/dvb-usb/dib0700_core.c
index 515f89dba199..92d5408684ac 100644
--- a/drivers/media/usb/dvb-usb/dib0700_core.c
+++ b/drivers/media/usb/dvb-usb/dib0700_core.c
@@ -213,7 +213,7 @@ static int dib0700_i2c_xfer_new(struct i2c_adapter *adap, struct i2c_msg *msg,
usb_rcvctrlpipe(d->udev, 0),
REQUEST_NEW_I2C_READ,
USB_TYPE_VENDOR | USB_DIR_IN,
- value, index, msg[i].buf,
+ value, index, st->buf,
msg[i].len,
USB_CTRL_GET_TIMEOUT);
if (result < 0) {
@@ -221,6 +221,14 @@ static int dib0700_i2c_xfer_new(struct i2c_adapter *adap, struct i2c_msg *msg,
break;
}

+ if (msg[i].len > sizeof(st->buf)) {
+ deb_info("buffer too small to fit %d bytes\n",
+ msg[i].len);
+ return -EIO;
+ }
+
+ memcpy(msg[i].buf, st->buf, msg[i].len);
+
deb_data("<<< ");
debug_dump(msg[i].buf, msg[i].len, deb_data);

@@ -238,6 +246,13 @@ static int dib0700_i2c_xfer_new(struct i2c_adapter *adap, struct i2c_msg *msg,
/* I2C ctrl + FE bus; */
st->buf[3] = ((gen_mode << 6) & 0xC0) |
((bus_mode << 4) & 0x30);
+
+ if (msg[i].len > sizeof(st->buf) - 4) {
+ deb_info("i2c message to big: %d\n",
+ msg[i].len);
+ return -EIO;
+ }
+
/* The Actual i2c payload */
memcpy(&st->buf[4], msg[i].buf, msg[i].len);

@@ -283,6 +298,11 @@ static int dib0700_i2c_xfer_legacy(struct i2c_adapter *adap,
/* fill in the address */
st->buf[1] = msg[i].addr << 1;
/* fill the buffer */
+ if (msg[i].len > sizeof(st->buf) - 2) {
+ deb_info("i2c xfer to big: %d\n",
+ msg[i].len);
+ return -EIO;
+ }
memcpy(&st->buf[2], msg[i].buf, msg[i].len);

/* write/read request */
@@ -299,6 +319,11 @@ static int dib0700_i2c_xfer_legacy(struct i2c_adapter *adap,
break;
}

+ if (msg[i + 1].len > sizeof(st->buf)) {
+ deb_info("i2c xfer buffer to small for %d\n",
+ msg[i].len);
+ return -EIO;
+ }
memcpy(msg[i + 1].buf, st->buf, msg[i + 1].len);

msg[i+1].len = len;
--
2.7.4

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