Commit f7134eea authored by David Fries's avatar David Fries Committed by Greg Kroah-Hartman
Browse files

w1_therm reference count family data 



A temperature conversion can take 750 ms and when possible the
w1_therm slave driver drops the bus_mutex to allow other bus
operations, but that includes operations such as a periodic slave
search, which can remove this slave when it is no longer detected.
If that happens the sl->family_data will be freed and set to NULL
causing w1_slave_show to crash when it wakes up.

Signed-off-by: default avatarDavid Fries <David@Fries.net>
Reported-By: default avatarThorsten Bschorr <thorsten@bschorr.de>
Tested-by: default avatarThorsten Bschorr <thorsten@bschorr.de>
Acked-by: default avatarEvgeniy Polyakov <zbr@ioremap.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent c3098356

drivers/w1/slaves/w1_therm.c

+47 −15
Original line number Diff line number Diff line
@@ -59,16 +59,32 @@ MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00)); 
static int w1_strong_pullup = 1;

module_param_named(strong_pullup, w1_strong_pullup, int, 0);



struct w1_therm_family_data {

	uint8_t rom[9];

	atomic_t refcnt;

};



/* return the address of the refcnt in the family data */

#define THERM_REFCNT(family_data) \

	(&((struct w1_therm_family_data*)family_data)->refcnt)



static int w1_therm_add_slave(struct w1_slave *sl)

{

	sl->family_data = kzalloc(9, GFP_KERNEL);

	sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),

		GFP_KERNEL);

	if (!sl->family_data)

		return -ENOMEM;

	atomic_set(THERM_REFCNT(sl->family_data), 1);

	return 0;

}



static void w1_therm_remove_slave(struct w1_slave *sl)

{

	int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));

	while(refcnt) {

		msleep(1000);

		refcnt = atomic_read(THERM_REFCNT(sl->family_data));

	}

	kfree(sl->family_data);

	sl->family_data = NULL;

}
@@ -194,13 +210,22 @@ static ssize_t w1_slave_show(struct device *device, 
	struct w1_slave *sl = dev_to_w1_slave(device);

	struct w1_master *dev = sl->master;

	u8 rom[9], crc, verdict, external_power;

	int i, max_trying = 10;

	int i, ret, max_trying = 10;

	ssize_t c = PAGE_SIZE;

	u8 *family_data = sl->family_data;



	ret = mutex_lock_interruptible(&dev->bus_mutex);

	if (ret != 0)

		goto post_unlock;



	i = mutex_lock_interruptible(&dev->bus_mutex);

	if (i != 0)

		return i;

	if(!sl->family_data)

	{

		ret = -ENODEV;

		goto pre_unlock;

	}



	/* prevent the slave from going away in sleep */

	atomic_inc(THERM_REFCNT(family_data));

	memset(rom, 0, sizeof(rom));



	while (max_trying--) {
@@ -230,17 +255,19 @@ static ssize_t w1_slave_show(struct device *device, 
				mutex_unlock(&dev->bus_mutex);



				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0)

					return -EINTR;

				if (sleep_rem != 0) {

					ret = -EINTR;

					goto post_unlock;

				}



				i = mutex_lock_interruptible(&dev->bus_mutex);

				if (i != 0)

					return i;

				ret = mutex_lock_interruptible(&dev->bus_mutex);

				if (ret != 0)

					goto post_unlock;

			} else if (!w1_strong_pullup) {

				sleep_rem = msleep_interruptible(tm);

				if (sleep_rem != 0) {

					mutex_unlock(&dev->bus_mutex);

					return -EINTR;

					ret = -EINTR;

					goto pre_unlock;

				}

			}
@@ -269,19 +296,24 @@ static ssize_t w1_slave_show(struct device *device, 
	c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",

			   crc, (verdict) ? "YES" : "NO");

	if (verdict)

		memcpy(sl->family_data, rom, sizeof(rom));

		memcpy(family_data, rom, sizeof(rom));

	else

		dev_warn(device, "Read failed CRC check\n");



	for (i = 0; i < 9; ++i)

		c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ",

			      ((u8 *)sl->family_data)[i]);

			      ((u8 *)family_data)[i]);



	c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",

		w1_convert_temp(rom, sl->family->fid));

	ret = PAGE_SIZE - c;



pre_unlock:

	mutex_unlock(&dev->bus_mutex);



	return PAGE_SIZE - c;

post_unlock:

	atomic_dec(THERM_REFCNT(family_data));

	return ret;

}



static int __init w1_therm_init(void)

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