4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhang Shurong <zhang_shurong@xxxxxxxxxxx>
[ Upstream commit 7bf744f2de0a848fb1d717f5831b03db96feae89 ]
In af9035_i2c_master_xfer, msg is controlled by user. When msg[i].buf
is null and msg[i].len is zero, former checks on msg[i].buf would be
passed. Malicious data finally reach af9035_i2c_master_xfer. If accessing
msg[i].buf[0] without sanity check, null ptr deref would happen.
We add check on msg[i].len to prevent crash.
Similar commit:
commit 0ed554fd769a
("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()")
Signed-off-by: Zhang Shurong <zhang_shurong@xxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
[ moved variable declaration to fix build issues in older kernels - gregkh ]
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/media/usb/dvb-usb-v2/af9035.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
--- a/drivers/media/usb/dvb-usb-v2/af9035.c
+++ b/drivers/media/usb/dvb-usb-v2/af9035.c
@@ -284,6 +284,7 @@ static int af9035_i2c_master_xfer(struct
struct dvb_usb_device *d = i2c_get_adapdata(adap);
struct state *state = d_to_priv(d);
int ret;
+ u32 reg;
if (mutex_lock_interruptible(&d->i2c_mutex) < 0)
return -EAGAIN;
@@ -336,8 +337,10 @@ static int af9035_i2c_master_xfer(struct
ret = -EOPNOTSUPP;
} else if ((msg[0].addr == state->af9033_i2c_addr[0]) ||
(msg[0].addr == state->af9033_i2c_addr[1])) {
+ if (msg[0].len < 3 || msg[1].len < 1)
+ return -EOPNOTSUPP;
/* demod access via firmware interface */
- u32 reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 |
+ reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 |
msg[0].buf[2];
if (msg[0].addr == state->af9033_i2c_addr[1])
@@ -395,17 +398,16 @@ static int af9035_i2c_master_xfer(struct
ret = -EOPNOTSUPP;
} else if ((msg[0].addr == state->af9033_i2c_addr[0]) ||
(msg[0].addr == state->af9033_i2c_addr[1])) {
+ if (msg[0].len < 3)
+ return -EOPNOTSUPP;
/* demod access via firmware interface */
- u32 reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 |
+ reg = msg[0].buf[0] << 16 | msg[0].buf[1] << 8 |
msg[0].buf[2];
if (msg[0].addr == state->af9033_i2c_addr[1])
reg |= 0x100000;
- ret = (msg[0].len >= 3) ? af9035_wr_regs(d, reg,
- &msg[0].buf[3],
- msg[0].len - 3)
- : -EOPNOTSUPP;
+ ret = af9035_wr_regs(d, reg, &msg[0].buf[3], msg[0].len - 3);
} else {
/* I2C write */
u8 buf[MAX_XFER_SIZE];
