| Date | Tue, 25 Jan 2022 20:20:38 +0100 | From | Pavel Machek <> | Subject | Re: [PATCH 4.4 066/114] media: m920x: dont use stack on USB reads |
| |
Hi!
> From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> > > [ Upstream commit a2ab06d7c4d6bfd0b545a768247a70463e977e27 ] > > Using stack-allocated pointers for USB message data don't work. > This driver is almost OK with that, except for the I2C read > logic. > > Fix it by using a temporary read buffer, just like on all other > calls to m920x_read().
Maybe the driver is buggy, but the fix is not okay.
> +++ b/drivers/media/usb/dvb-usb/m920x.c > @@ -284,6 +284,13 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu > /* Should check for ack here, if we knew how. */ > } > if (msg[i].flags & I2C_M_RD) { > + char *read = kmalloc(1, GFP_KERNEL); > + if (!read) { > + ret = -ENOMEM; > + kfree(read);
kfree(NULL). You probably did not want to do that.
> + goto unlock; > + } > + > for (j = 0; j < msg[i].len; j++) { > /* Last byte of transaction? > * Send STOP, otherwise send ACK. */ > @@ -291,9 +298,12 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu > > if ((ret = m920x_read(d->udev, M9206_I2C, 0x0, > 0x20 | stop, > - &msg[i].buf[j], 1)) != 0) > + read, 1)) != 0) > goto unlock;
Memory leak here.
> + msg[i].buf[j] = read[0]; > } > + > + kfree(read); > } else { > for (j = 0; j < msg[i].len; j++) { > /* Last byte of transaction? Then send STOP. */
Plus really running malloc in a loop like that looks strange.
Anyway, this should stop the leaks.
Best regards, Pavel
diff --git a/drivers/media/usb/dvb-usb/m920x.c b/drivers/media/usb/dvb-usb/m920x.c index 691e05833db1..da81fa189b5d 100644 --- a/drivers/media/usb/dvb-usb/m920x.c +++ b/drivers/media/usb/dvb-usb/m920x.c @@ -277,7 +277,6 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu char *read = kmalloc(1, GFP_KERNEL); if (!read) { ret = -ENOMEM; - kfree(read); goto unlock; } @@ -288,8 +287,10 @@ static int m920x_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int nu if ((ret = m920x_read(d->udev, M9206_I2C, 0x0, 0x20 | stop, - read, 1)) != 0) + read, 1)) != 0) { + kfree(read); goto unlock; + } msg[i].buf[j] = read[0]; } -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany[unhandled content-type:application/pgp-signature] |