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media: dvb-usb-v2: af9035: Fix null-ptr-deref in af9035_i2c_master_xfer

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[ 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@foxmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ moved variable declaration to fix build issues in older kernels - gregkh ]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Zhang Shurong 2023-07-06 00:06:54 +08:00 committed by Greg Kroah-Hartman
parent 9f3b2b6668
commit 6c01ef65de
1 changed files with 8 additions and 6 deletions
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14
drivers/media/usb/dvb-usb-v2/af9035.c
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@ -269,6 +269,7 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
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;
@ -321,8 +322,10 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
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])
@ -380,17 +383,16 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
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];