Increase SMBus max block size to 255

index d2d32c0fd8c3..8b723d684f54 100644
@@ -295,7 +295,8 @@ static void i2c_smbus_try_get_dmabuf(struct i2c_msg *msg, u8 init_val)
 	bool is_read = msg->flags & I2C_M_RD;
 	unsigned char *dma_buf;
 
-	dma_buf = kzalloc(I2C_SMBUS_BLOCK_MAX + (is_read ? 2 : 3), GFP_KERNEL);
+	dma_buf = kzalloc(I2C_SMBUS_V3_BLOCK_MAX + (is_read ? 2 : 3),
+		GFP_KERNEL);
 	if (!dma_buf)
 		return;
 

@@ -321,9 +322,10 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 	 * initialize most things with sane defaults, to keep the code below
 	 * somewhat simpler.
 	 */
-	unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
-	unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
+	unsigned char msgbuf0[I2C_SMBUS_V3_BLOCK_MAX+3];
+	unsigned char msgbuf1[I2C_SMBUS_V3_BLOCK_MAX+2];
 	int nmsgs = read_write == I2C_SMBUS_READ ? 2 : 1;
+	u16 block_max;
 	u8 partial_pec = 0;
 	int status;
 	struct i2c_msg msg[2] = {

@@ -342,6 +344,10 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 	bool wants_pec = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
 			  && size != I2C_SMBUS_I2C_BLOCK_DATA);
 
+	/* Drivers must opt in to 255 byte max block size */
+	block_max = i2c_check_functionality(adapter, I2C_FUNC_SMBUS_V3_BLOCK)
+			? I2C_SMBUS_V3_BLOCK_MAX : I2C_SMBUS_BLOCK_MAX;
+
 	msgbuf0[0] = command;
 	switch (size) {
 	case I2C_SMBUS_QUICK:

@@ -391,7 +397,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 			i2c_smbus_try_get_dmabuf(&msg[1], 0);
 		} else {
 			msg[0].len = data->block[0] + 2;
-			if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
+			if (msg[0].len > block_max + 2) {
 				dev_err(&adapter->dev,
 					"Invalid block write size %d\n",
 					data->block[0]);

@@ -405,7 +411,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 	case I2C_SMBUS_BLOCK_PROC_CALL:
 		nmsgs = 2; /* Another special case */
 		read_write = I2C_SMBUS_READ;
-		if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+		if (data->block[0] > block_max) {
 			dev_err(&adapter->dev,
 				"Invalid block write size %d\n",
 				data->block[0]);

@@ -422,7 +428,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 		i2c_smbus_try_get_dmabuf(&msg[1], 0);
 		break;
 	case I2C_SMBUS_I2C_BLOCK_DATA:
-		if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+		if (data->block[0] > block_max) {
 			dev_err(&adapter->dev, "Invalid block %s size %d\n",
 				read_write == I2C_SMBUS_READ ? "read" : "write",
 				data->block[0]);

@@ -490,7 +496,7 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
 			break;
 		case I2C_SMBUS_BLOCK_DATA:
 		case I2C_SMBUS_BLOCK_PROC_CALL:
-			if (msg[1].buf[0] > I2C_SMBUS_BLOCK_MAX) {
+			if (msg[1].buf[0] > block_max) {
 				dev_err(&adapter->dev,
 					"Invalid block size returned: %d\n",
 					msg[1].buf[0]);

index e8f2ac8c9c3d..57170468301e 100644
@@ -50,6 +50,19 @@ typedef int (*i2c_slave_cb_t)(struct i2c_client *client,
 struct module;
 struct property_entry;
 
+/* SMBus 3.0 extends the maximum block read/write size to 255 (from 32).
+ * The larger size is only supported by some drivers, indicated by
+ * the I2C_FUNC_SMBUS_V3_BLOCK functionality bit.
+ */
+#define I2C_SMBUS_V3_BLOCK_MAX	255	/* As specified in SMBus 3.0 standard */
+
+/* Note compatibility definition in uapi header with 32 byte block */
+union i2c_smbus_data {
+	__u8 byte;
+	__u16 word;
+	__u8 block[I2C_SMBUS_V3_BLOCK_MAX + 1]; /* block[0] is used for length */
+};
+
 #if IS_ENABLED(CONFIG_I2C)
 /* Return the Frequency mode string based on the bus frequency */
 const char *i2c_freq_mode_string(u32 bus_freq_hz);

index 92326ebde350..7b7d90b50cf0 100644
@@ -108,6 +108,7 @@ struct i2c_msg {
 #define I2C_FUNC_SMBUS_READ_I2C_BLOCK	0x04000000 /* I2C-like block xfer  */
 #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 */
 
 #define I2C_FUNC_SMBUS_BYTE		(I2C_FUNC_SMBUS_READ_BYTE | \
 					 I2C_FUNC_SMBUS_WRITE_BYTE)

@@ -137,13 +138,15 @@ struct i2c_msg {
 /*
  * Data for SMBus Messages
  */
-#define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus standard */
+#define I2C_SMBUS_BLOCK_MAX	32	/* As specified in SMBus 2.0 standard */
+#ifndef __KERNEL__
 union 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 */
 };
+#endif
 
 /* i2c_smbus_xfer read or write markers */
 #define I2C_SMBUS_READ	1

index 6ef38a8ee95c..b99780c2a55d 100644
@@ -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;
 	}

index 1c4cec4ddd84..46ce31d42f7d 100644
@@ -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 {

index 7b7d90b50cf0..c3534ab1ae53 100644
@@ -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)

index 724bf30600d6..04cb5d08daf5 100644
@@ -533,7 +533,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
 		msg->buf[bus->buf_index++] = recv_byte;
 
 		if (msg->flags & I2C_M_RECV_LEN) {
-			if (unlikely(recv_byte > I2C_SMBUS_BLOCK_MAX)) {
+			if (unlikely(recv_byte > I2C_SMBUS_V3_BLOCK_MAX)) {
 				bus->cmd_err = -EPROTO;
 				aspeed_i2c_do_stop(bus);
 				goto out_no_complete;

@@ -718,7 +718,8 @@ static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
 
 static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
 {
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
+		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_V3_BLOCK;
 }
 
 #if IS_ENABLED(CONFIG_I2C_SLAVE)