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

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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>
This commit is contained in:
Zhang Shurong 2023-07-06 00:06:54 +08:00 committed by Hans Verkuil
parent d5b3214a92
commit 7bf744f2de
1 changed files with 5 additions and 4 deletions
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9
drivers/media/usb/dvb-usb-v2/af9035.c
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@ -322,6 +322,8 @@ 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 |
msg[0].buf[2];
@ -381,6 +383,8 @@ 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 |
msg[0].buf[2];
@ -388,10 +392,7 @@ static int af9035_i2c_master_xfer(struct i2c_adapter *adap,
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];