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V4L/DVB (11832): dibusb_mc: fix i2c to not corrupt eeprom in case of strange read pattern

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dibusb_i2c_xfer seems to do things very dangerous :
it assumes that it get only write/read request or write request.

That means that read can be understood as write. For example a program
doing
file = open("/dev/i2c-x", O_RDWR);
    ioctl(file, I2C_SLAVE, 0x50)
read(file, data, 10)
    will corrupt the eeprom as it will be understood as a write.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Signed-off-by: Patrick Boettcher <pb@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
matthieu castet 2009-05-20 05:42:33 -03:00 committed by Mauro Carvalho Chehab
parent a9b8fe30a6
commit 81dae6716f
1 changed files with 5 additions and 2 deletions
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7
drivers/media/dvb/dvb-usb/dibusb-common.c
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@ -133,14 +133,17 @@ static int dibusb_i2c_xfer(struct i2c_adapter *adap,struct i2c_msg msg[],int num
for (i = 0; i < num; i++) { for (i = 0; i < num; i++) {
/* write/read request */ /* write/read request */
if (i+1 < num && (msg[i+1].flags & I2C_M_RD)) { if (i+1 < num && (msg[i].flags & I2C_M_RD) == 0
&& (msg[i+1].flags & I2C_M_RD)) {
if (dibusb_i2c_msg(d, msg[i].addr, msg[i].buf,msg[i].len, if (dibusb_i2c_msg(d, msg[i].addr, msg[i].buf,msg[i].len,
msg[i+1].buf,msg[i+1].len) < 0) msg[i+1].buf,msg[i+1].len) < 0)
break; break;
i++; i++;
} else } else if ((msg[i].flags & I2C_M_RD) == 0) {
if (dibusb_i2c_msg(d, msg[i].addr, msg[i].buf,msg[i].len,NULL,0) < 0) if (dibusb_i2c_msg(d, msg[i].addr, msg[i].buf,msg[i].len,NULL,0) < 0)
break; break;
} else
break;
} }
mutex_unlock(&d->i2c_mutex); mutex_unlock(&d->i2c_mutex);