I2C_SMBUS is limited to 32 bytes due to compatibility with the
32 byte i2c_smbus_data.block
I2C_RDWR allows larger transfers if sufficient sized buffers are passed.
Signed-off-by: Matt Johnston <matt@xxxxxxxxxxxxxxxxxxxx>
---
drivers/i2c/i2c-dev.c | 92 ++++++++++++++++++++++++++++++------
include/uapi/linux/i2c-dev.h | 2 +
include/uapi/linux/i2c.h | 2 +
3 files changed, 82 insertions(+), 14 deletions(-)
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 6ef38a8ee95c..b99780c2a55d 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -44,6 +44,24 @@ struct i2c_dev {
struct cdev cdev;
};
+/* The userspace union i2c_smbus_data for I2C_SMBUS ioctl is limited
+ * to 32 bytes (I2C_SMBUS_BLOCK_MAX) for compatibility.
+ */
+union compat_i2c_smbus_data {
+ __u8 byte;
+ __u16 word;
+ __u8 block[I2C_SMBUS_BLOCK_MAX + 2]; /* block[0] is used for length */
+ /* and one more for user-space compatibility */
+};
+
+/* Must match i2c-dev.h definition with compat .data member */
+struct i2c_smbus_ioctl_data {
+ __u8 read_write;
+ __u8 command;
+ __u32 size;
+ union compat_i2c_smbus_data __user *data;
+};
+
#define I2C_MINORS (MINORMASK + 1)
static LIST_HEAD(i2c_dev_list);
static DEFINE_SPINLOCK(i2c_dev_list_lock);
@@ -235,14 +253,17 @@ static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
unsigned nmsgs, struct i2c_msg *msgs)
{
- u8 __user **data_ptrs;
+ u8 __user **data_ptrs = NULL;
+ u16 *orig_lens = NULL;
int i, res;
+ res = -ENOMEM;
data_ptrs = kmalloc_array(nmsgs, sizeof(u8 __user *), GFP_KERNEL);
- if (data_ptrs == NULL) {
- kfree(msgs);
- return -ENOMEM;
- }
+ if (data_ptrs == NULL)
+ goto out;
+ orig_lens = kmalloc_array(nmsgs, sizeof(u16), GFP_KERNEL);
+ if (orig_lens == NULL)
+ goto out;
res = 0;
for (i = 0; i < nmsgs; i++) {
@@ -253,12 +274,29 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
}
data_ptrs[i] = (u8 __user *)msgs[i].buf;
- msgs[i].buf = memdup_user(data_ptrs[i], msgs[i].len);
+ msgs[i].buf = NULL;
+ if (msgs[i].len < 1) {
+ /* Sanity check */
+ res = -EINVAL;
+ break;
+
+ }
+ /* Allocate a larger buffer to accommodate possible 255 byte
+ * blocks. Read results will be dropped later
+ * if they are too large for the original length. */
+ orig_lens[i] = msgs[i].len;
+ msgs[i].buf = kmalloc(msgs[i].len + I2C_SMBUS_V3_BLOCK_MAX,
+ GFP_USER | __GFP_NOWARN);
if (IS_ERR(msgs[i].buf)) {
res = PTR_ERR(msgs[i].buf);
break;
}
- /* memdup_user allocates with GFP_KERNEL, so DMA is ok */
+ if (copy_from_user(msgs[i].buf, data_ptrs[i], msgs[i].len)) {
+ kfree(msgs[i].buf);
+ res = -EFAULT;
+ break;
+ }
+ /* Buffer from kmalloc, so DMA is ok */
msgs[i].flags |= I2C_M_DMA_SAFE;
/*
@@ -274,7 +312,7 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
*/
if (msgs[i].flags & I2C_M_RECV_LEN) {
if (!(msgs[i].flags & I2C_M_RD) ||
- msgs[i].len < 1 || msgs[i].buf[0] < 1 ||
+ msgs[i].buf[0] < 1 ||
msgs[i].len < msgs[i].buf[0] +
I2C_SMBUS_BLOCK_MAX) {
i++;
@@ -297,12 +335,16 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
res = i2c_transfer(client->adapter, msgs, nmsgs);
while (i-- > 0) {
if (res >= 0 && (msgs[i].flags & I2C_M_RD)) {
- if (copy_to_user(data_ptrs[i], msgs[i].buf,
- msgs[i].len))
+ if (orig_lens[i] < msgs[i].len)
+ res = -EINVAL;
+ else if (copy_to_user(data_ptrs[i], msgs[i].buf,
+ msgs[i].len))
res = -EFAULT;
}
kfree(msgs[i].buf);
}
+out:
+ kfree(orig_lens);
kfree(data_ptrs);
kfree(msgs);
return res;
@@ -310,7 +352,7 @@ static noinline int i2cdev_ioctl_rdwr(struct i2c_client *client,
static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
u8 read_write, u8 command, u32 size,
- union i2c_smbus_data __user *data)
+ union compat_i2c_smbus_data __user *data)
{
union i2c_smbus_data temp = {};
int datasize, res;
@@ -371,6 +413,16 @@ static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
if (copy_from_user(&temp, data, datasize))
return -EFAULT;
}
+ if ((size == I2C_SMBUS_BLOCK_PROC_CALL ||
+ size == I2C_SMBUS_I2C_BLOCK_DATA ||
+ size == I2C_SMBUS_BLOCK_DATA) &&
+ read_write == I2C_SMBUS_WRITE &&
+ temp.block[0] > I2C_SMBUS_BLOCK_MAX) {
+ /* Don't accept writes larger than the buffer size */
+ dev_dbg(&client->adapter->dev, "block write is too large");
+ return -EINVAL;
+
+ }
if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
/* Convert old I2C block commands to the new
convention. This preserves binary compatibility. */
@@ -380,9 +432,21 @@ static noinline int i2cdev_ioctl_smbus(struct i2c_client *client,
}
res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
read_write, command, size, &temp);
- if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
- (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
- (read_write == I2C_SMBUS_READ))) {
+ if (res)
+ return res;
+ if ((size == I2C_SMBUS_BLOCK_PROC_CALL ||
+ size == I2C_SMBUS_I2C_BLOCK_DATA ||
+ size == I2C_SMBUS_BLOCK_DATA) &&
+ read_write == I2C_SMBUS_READ &&
+ temp.block[0] > I2C_SMBUS_BLOCK_MAX) {
+ /* Don't accept reads larger than the buffer size */
+ dev_dbg(&client->adapter->dev, "block read is too large");
+ return -EINVAL;
+
+ }
+ if ((size == I2C_SMBUS_PROC_CALL) ||
+ (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
+ (read_write == I2C_SMBUS_READ)) {
if (copy_to_user(data, &temp, datasize))
return -EFAULT;
}
diff --git a/include/uapi/linux/i2c-dev.h b/include/uapi/linux/i2c-dev.h
index 1c4cec4ddd84..46ce31d42f7d 100644
--- a/include/uapi/linux/i2c-dev.h
+++ b/include/uapi/linux/i2c-dev.h
@@ -39,12 +39,14 @@
/* This is the structure as used in the I2C_SMBUS ioctl call */
+#ifndef __KERNEL__
struct i2c_smbus_ioctl_data {
__u8 read_write;
__u8 command;
__u32 size;
union i2c_smbus_data __user *data;
};
+#endif
/* This is the structure as used in the I2C_RDWR ioctl call */
struct i2c_rdwr_ioctl_data {
diff --git a/include/uapi/linux/i2c.h b/include/uapi/linux/i2c.h
index 7b7d90b50cf0..c3534ab1ae53 100644
--- a/include/uapi/linux/i2c.h
+++ b/include/uapi/linux/i2c.h
@@ -109,6 +109,8 @@ struct i2c_msg {
#define I2C_FUNC_SMBUS_WRITE_I2C_BLOCK 0x08000000 /* w/ 1-byte reg. addr. */
#define I2C_FUNC_SMBUS_HOST_NOTIFY 0x10000000 /* SMBus 2.0 or later */
#define I2C_FUNC_SMBUS_V3_BLOCK 0x20000000 /* Device supports 255 byte block */
+ /* Note that I2C_SMBUS ioctl only */
+ /* supports a 32 byte block */
#define I2C_FUNC_SMBUS_BYTE (I2C_FUNC_SMBUS_READ_BYTE | \
I2C_FUNC_SMBUS_WRITE_BYTE)
--
2.30.2
