HID: ft260: add usb hid to i2c host bridge driver
Subsystems (2)
Hello Michael Zaidman,
The patch 6a82582d9fa4: "HID: ft260: add usb hid to i2c host bridge driver" from Feb 19, 2021, leads to the following static checker warning:
drivers/hid/hid-ft260.c:441 ft260_smbus_write() error: '__memcpy()' '&rep->data[1]' too small (59 vs 255)
drivers/hid/hid-ft260.c
423 static int ft260_smbus_write(struct ft260_device *dev, u8 addr, u8 cmd,
424 u8 *data, u8 data_len, u8 flag)
425 {
426 int ret = 0;
427 int len = 4;
428
429 struct ft260_i2c_write_request_report *rep =
430 (struct ft260_i2c_write_request_report *)dev->write_buf;
431
432 rep->address = addr;
433 rep->data[0] = cmd;
434 rep->length = data_len + 1;
435 rep->flag = flag;
436 len += rep->length;
437
438 rep->report = FT260_I2C_DATA_REPORT_ID(len);
439
440 if (data_len > 0)
441 memcpy(&rep->data[1], data, data_len);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Smatch says that this can be called from the i2cdev_ioctl_smbus() function.
i2cdev_ioctl_smbus()
--> i2c_smbus_xfer
--> __i2c_smbus_xfer
--> ft260_smbus_xfer
--> ft260_smbus_write 442
443 ft260_dbg("rep %#02x addr %#02x cmd %#02x datlen %d replen %d\n",
444 rep->report, addr, cmd, rep->length, len);
445
446 ret = ft260_hid_output_report_check_status(dev, (u8 *)rep, len);
447
448 return ret;
449 }
regards,
dan carpenter
Quoted 30 lines · Dan Carpenter
Hello Michael Zaidman,
The patch
6a82582d9fa4: "HID: ft260: add usb hid to i2c host bridge driver" from Feb 19, 2021, leads to the following static checker warning:drivers/hid/hid-ft260.c:441 ft260_smbus_write() error: '__memcpy()' '&rep->data[1]' too small (59 vs 255)
drivers/hid/hid-ft260.c
423 static int ft260_smbus_write(structft260_device*dev, u8 addr, u8 cmd,
424 u8 *data, u8data_len, u8 flag)425 { 426 int ret = 0; 427 int len = 4; 428 429 struct ft260_i2c_write_request_report *rep = 430 (struct ft260_i2c_write_request_report *)dev->write_buf; 431 432 rep->address = addr; 433 rep->data[0] = cmd; 434 rep->length = data_len + 1; 435 rep->flag = flag; 436 len += rep->length; 437 438 rep->report = FT260_I2C_DATA_REPORT_ID(len); 439 440 if (data_len > 0) 441 memcpy(&rep->data[1], data, data_len); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Quoted 2 lines
Smatch says that this can be called from the
i2cdev_ioctl_smbus()function.
Hi Dan,
This is an example of a false-positive static checker warning.
The maximum data size that the i2cdev_ioctl_smbus() can pass to the i2c_smbus_xfer() is sizeof(data->block) which is (I2C_SMBUS_BLOCK_MAX + 2) or 34 bytes. Thus, no need to check the data_len against 59 here.
Regrads,
Michael
Quoted 18 lines
i2cdev_ioctl_smbus()
-->i2c_smbus_xfer--> __i2c_smbus_xfer --> ft260_smbus_xfer --> ft260_smbus_write442 443 ft260_dbg("rep %#02x addr %#02x cmd %#02x datlen %d replen %d\n", 444 rep->report, addr, cmd, rep->length, len); 445 446 ret = ft260_hid_output_report_check_status(dev, (u8 *)rep, len); 447 448 return ret; 449 }regards,
dan carpenter
Quoted 34 lines · Michael Zaidman
Quoted 30 lines · Dan Carpenter
Hello Michael Zaidman,
The patch
6a82582d9fa4: "HID: ft260: add usb hid to i2c host bridge driver" from Feb 19, 2021, leads to the following static checker warning:drivers/hid/hid-ft260.c:441 ft260_smbus_write() error: '__memcpy()' '&rep->data[1]' too small (59 vs 255)
drivers/hid/hid-ft260.c
423 static int ft260_smbus_write(structft260_device*dev, u8 addr, u8 cmd,
424 u8 *data, u8data_len, u8 flag)425 { 426 int ret = 0; 427 int len = 4; 428 429 struct ft260_i2c_write_request_report *rep = 430 (struct ft260_i2c_write_request_report *)dev->write_buf; 431 432 rep->address = addr; 433 rep->data[0] = cmd; 434 rep->length = data_len + 1; 435 rep->flag = flag; 436 len += rep->length; 437 438 rep->report = FT260_I2C_DATA_REPORT_ID(len); 439 440 if (data_len > 0) 441 memcpy(&rep->data[1], data, data_len); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Quoted 2 lines
Smatch says that this can be called from the
i2cdev_ioctl_smbus()function.
Quoted 14 lines
Hi Dan,
This is an example of a false-positive static checker warning.
The maximum data size that the
i2cdev_ioctl_smbus()can pass to thei2c_smbus_xfer()issizeof(data->block)which is (I2C_SMBUS_BLOCK_MAX+ 2) or 34 bytes. Thus, no need to check thedata_lenagainst 59 here.Quoted 6 lines
i2cdev_ioctl_smbus()
-->i2c_smbus_xfer--> __i2c_smbus_xfer --> ft260_smbus_xfer --> ft260_smbus_write
It's actually me who misunderstood the Smatch warning. Smatch is not complaining about data_len, it's data->block[0] which is user controlled and only for the I2C_SMBUS_I2C_BLOCK_DATA command.
The call tree is the same. I've looked at it again. Here is how i2cdev_ioctl_smbus() looks like:
drivers/i2c/i2c-dev.c
355 return -EINVAL;
356 }
357
358 if ((size == I2C_SMBUS_BYTE_DATA) ||
359 (size == I2C_SMBUS_BYTE))
360 datasize = sizeof(data->byte);
361 else if ((size == I2C_SMBUS_WORD_DATA) ||
362 (size == I2C_SMBUS_PROC_CALL))
363 datasize = sizeof(data->word);
364 else /* size == smbus block, i2c block, or block proc. call */
365 datasize = sizeof(data->block);
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 366
367 if ((size == I2C_SMBUS_PROC_CALL) ||
368 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
369 (size == I2C_SMBUS_I2C_BLOCK_DATA) ||
^^^^^^^^^^^^^^^^^^^^^^^^
370 (read_write == I2C_SMBUS_WRITE)) {
371 if (copy_from_user(&temp, data, datasize))
^^^^temp.block[0] is user controlled.
372 return -EFAULT;
373 }
374 if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) {
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 375 /* Convert old I2C block commands to the new
376 convention. This preserves binary compatibility. */
377 size = I2C_SMBUS_I2C_BLOCK_DATA;
378 if (read_write == I2C_SMBUS_READ)
379 temp.block[0] = I2C_SMBUS_BLOCK_MAX;
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Except for size BROKEN
380 }
381 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
382 read_write, command, size, &temp);
^^^^^ 383 if (!res && ((size == I2C_SMBUS_PROC_CALL) ||
384 (size == I2C_SMBUS_BLOCK_PROC_CALL) ||
385 (read_write == I2C_SMBUS_READ))) {
386 if (copy_to_user(data, &temp, datasize))
387 return -EFAULT;
388 }The rest of the call tree seems straight forward but it's possible I have missed somewhere that checks data[0]. Here is how ft260_smbus_xfer() looks like.
drivers/hid/hid-ft260.c
655 case I2C_SMBUS_BLOCK_DATA:
656 if (read_write == I2C_SMBUS_READ) {
657 ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
658 FT260_FLAG_START);
659 if (ret)
660 goto smbus_exit;
661
662 ret = ft260_i2c_read(dev, addr, data->block,
663 data->block[0] + 1,
664 FT260_FLAG_START_STOP_REPEATED);
665 } else {
666 ret = ft260_smbus_write(dev, addr, cmd, data->block,
667 data->block[0] + 1,
668 FT260_FLAG_START_STOP);
669 }
670 break;
671 case I2C_SMBUS_I2C_BLOCK_DATA:
672 if (read_write == I2C_SMBUS_READ) {
673 ret = ft260_smbus_write(dev, addr, cmd, NULL, 0,
674 FT260_FLAG_START);
675 if (ret)
676 goto smbus_exit;
677
678 ret = ft260_i2c_read(dev, addr, data->block + 1,
679 data->block[0],
680 FT260_FLAG_START_STOP_REPEATED);
681 } else {
682 ret = ft260_smbus_write(dev, addr, cmd, data->block + 1,
683 data->block[0],
^^^^^^^^^^^^^^
Boom. Dead.
684 FT260_FLAG_START_STOP);
685 }
686 break;
687 default:
688 hid_err(hdev, "unsupported smbus transaction size %d\n", size);
689 ret = -EOPNOTSUPP;
690 }
regards,
dan carpenter
Quoted 106 lines · Dan Carpenter
Quoted 34 lines · Michael Zaidman
Quoted 30 lines · Dan Carpenter
Hello Michael Zaidman,
The patch
6a82582d9fa4: "HID: ft260: add usb hid to i2c host bridge driver" from Feb 19, 2021, leads to the following static checker warning:drivers/hid/hid-ft260.c:441 ft260_smbus_write() error: '__memcpy()' '&rep->data[1]' too small (59 vs 255)
drivers/hid/hid-ft260.c
423 static int ft260_smbus_write(structft260_device*dev, u8 addr, u8 cmd,
424 u8 *data, u8data_len, u8 flag)425 { 426 int ret = 0; 427 int len = 4; 428 429 struct ft260_i2c_write_request_report *rep = 430 (struct ft260_i2c_write_request_report *)dev->write_buf; 431 432 rep->address = addr; 433 rep->data[0] = cmd; 434 rep->length = data_len + 1; 435 rep->flag = flag; 436 len += rep->length; 437 438 rep->report = FT260_I2C_DATA_REPORT_ID(len); 439 440 if (data_len > 0) 441 memcpy(&rep->data[1], data, data_len); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Quoted 2 lines
Smatch says that this can be called from the
i2cdev_ioctl_smbus()function.Quoted 14 lines
Hi Dan,
This is an example of a false-positive static checker warning.
The maximum data size that the
i2cdev_ioctl_smbus()can pass to thei2c_smbus_xfer()issizeof(data->block)which is (I2C_SMBUS_BLOCK_MAX+ 2) or 34 bytes. Thus, no need to check thedata_lenagainst 59 here.Quoted 6 lines
i2cdev_ioctl_smbus()
-->i2c_smbus_xfer--> __i2c_smbus_xfer --> ft260_smbus_xfer --> ft260_smbus_writeIt's actually me who misunderstood the Smatch warning. Smatch is not complaining about
data_len, it's data->block[0] which is user controlled and only for theI2C_SMBUS_I2C_BLOCK_DATAcommand.The call tree is the same. I've looked at it again. Here is how
i2cdev_ioctl_smbus()looks like:
drivers/i2c/i2c-dev.c355 return -EINVAL; 356 } 357 358 if ((size == I2C_SMBUS_BYTE_DATA) || 359 (size == I2C_SMBUS_BYTE)) 360 datasize = sizeof(data->byte); 361 else if ((size == I2C_SMBUS_WORD_DATA) || 362 (size == I2C_SMBUS_PROC_CALL)) 363 datasize = sizeof(data->word); 364 else /* size == smbus block, i2c block, or block proc. call */ 365 datasize = sizeof(data->block); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 366 367 if ((size == I2C_SMBUS_PROC_CALL) || 368 (size == I2C_SMBUS_BLOCK_PROC_CALL) || 369 (size == I2C_SMBUS_I2C_BLOCK_DATA) || ^^^^^^^^^^^^^^^^^^^^^^^^ 370 (read_write == I2C_SMBUS_WRITE)) { 371 if (copy_from_user(&temp, data, datasize)) ^^^^temp.block[0] is user controlled.
372 return -EFAULT; 373 } 374 if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) { ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^375 /* Convert old I2C block commands to the new 376 convention. This preserves binary compatibility. */ 377 size = I2C_SMBUS_I2C_BLOCK_DATA; 378 if (read_write == I2C_SMBUS_READ) 379 temp.block[0] = I2C_SMBUS_BLOCK_MAX; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Except for size BROKEN
380 } 381 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags, 382 read_write, command, size, &temp); ^^^^^ 383 if (!res && ((size == I2C_SMBUS_PROC_CALL) || 384 (size == I2C_SMBUS_BLOCK_PROC_CALL) || 385 (read_write == I2C_SMBUS_READ))) { 386 if (copy_to_user(data, &temp, datasize)) 387 return -EFAULT; 388 }
Quoted 3 lines
The rest of the call tree seems straight forward but it's possible I have missed somewhere that checks data[0]. Here is how
ft260_smbus_xfer()looks like.
Oh, you are right. Despite that the SMbus block transaction limits the maximum number of bytes to 32, nothing prevents a user from specifying via ioctl a larger data size than the ft260 can handle in a single transfer.
I am going to fix it in the ft260_smbus_write (with your Signed-off-by), but perhaps we should fix it in the first place, in the i2cdev_ioctl_smbus routine? What do you think?
Quoted 46 lines
drivers/hid/hid-ft260.c
655 caseI2C_SMBUS_BLOCK_DATA:656 if (read_write == I2C_SMBUS_READ) { 657 ret = ft260_smbus_write(dev, addr, cmd, NULL, 0, 658 FT260_FLAG_START); 659 if (ret) 660 goto smbus_exit; 661 662 ret = ft260_i2c_read(dev, addr, data->block, 663 data->block[0] + 1, 664 FT260_FLAG_START_STOP_REPEATED); 665 } else { 666 ret = ft260_smbus_write(dev, addr, cmd, data->block, 667 data->block[0] + 1, 668 FT260_FLAG_START_STOP); 669 } 670 break; 671 case I2C_SMBUS_I2C_BLOCK_DATA: 672 if (read_write == I2C_SMBUS_READ) { 673 ret = ft260_smbus_write(dev, addr, cmd, NULL, 0, 674 FT260_FLAG_START); 675 if (ret) 676 goto smbus_exit; 677 678 ret = ft260_i2c_read(dev, addr, data->block + 1, 679 data->block[0], 680 FT260_FLAG_START_STOP_REPEATED); 681 } else { 682 ret = ft260_smbus_write(dev, addr, cmd, data->block + 1, 683 data->block[0], ^^^^^^^^^^^^^^Boom. Dead.
684 FT260_FLAG_START_STOP); 685 } 686 break; 687 default: 688 hid_err(hdev, "unsupported smbus transaction size %d\n", size); 689 ret = -EOPNOTSUPP; 690 }regards,
dan carpenter
Quoted 111 lines · Michael Zaidman
Quoted 106 lines · Dan Carpenter
Quoted 34 lines · Michael Zaidman
Quoted 30 lines · Dan Carpenter
Hello Michael Zaidman,
The patch
6a82582d9fa4: "HID: ft260: add usb hid to i2c host bridge driver" from Feb 19, 2021, leads to the following static checker warning:drivers/hid/hid-ft260.c:441 ft260_smbus_write() error: '__memcpy()' '&rep->data[1]' too small (59 vs 255)
drivers/hid/hid-ft260.c
423 static int ft260_smbus_write(structft260_device*dev, u8 addr, u8 cmd,
424 u8 *data, u8data_len, u8 flag)425 { 426 int ret = 0; 427 int len = 4; 428 429 struct ft260_i2c_write_request_report *rep = 430 (struct ft260_i2c_write_request_report *)dev->write_buf; 431 432 rep->address = addr; 433 rep->data[0] = cmd; 434 rep->length = data_len + 1; 435 rep->flag = flag; 436 len += rep->length; 437 438 rep->report = FT260_I2C_DATA_REPORT_ID(len); 439 440 if (data_len > 0) 441 memcpy(&rep->data[1], data, data_len); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Quoted 2 lines
Smatch says that this can be called from the
i2cdev_ioctl_smbus()function.Quoted 14 lines
Hi Dan,
This is an example of a false-positive static checker warning.
The maximum data size that the
i2cdev_ioctl_smbus()can pass to thei2c_smbus_xfer()issizeof(data->block)which is (I2C_SMBUS_BLOCK_MAX+ 2) or 34 bytes. Thus, no need to check thedata_lenagainst 59 here.Quoted 6 lines
i2cdev_ioctl_smbus()
-->i2c_smbus_xfer--> __i2c_smbus_xfer --> ft260_smbus_xfer --> ft260_smbus_writeIt's actually me who misunderstood the Smatch warning. Smatch is not complaining about
data_len, it's data->block[0] which is user controlled and only for theI2C_SMBUS_I2C_BLOCK_DATAcommand.The call tree is the same. I've looked at it again. Here is how
i2cdev_ioctl_smbus()looks like:
drivers/i2c/i2c-dev.c355 return -EINVAL; 356 } 357 358 if ((size == I2C_SMBUS_BYTE_DATA) || 359 (size == I2C_SMBUS_BYTE)) 360 datasize = sizeof(data->byte); 361 else if ((size == I2C_SMBUS_WORD_DATA) || 362 (size == I2C_SMBUS_PROC_CALL)) 363 datasize = sizeof(data->word); 364 else /* size == smbus block, i2c block, or block proc. call */ 365 datasize = sizeof(data->block); ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 366 367 if ((size == I2C_SMBUS_PROC_CALL) || 368 (size == I2C_SMBUS_BLOCK_PROC_CALL) || 369 (size == I2C_SMBUS_I2C_BLOCK_DATA) || ^^^^^^^^^^^^^^^^^^^^^^^^ 370 (read_write == I2C_SMBUS_WRITE)) { 371 if (copy_from_user(&temp, data, datasize)) ^^^^temp.block[0] is user controlled.
372 return -EFAULT; 373 } 374 if (size == I2C_SMBUS_I2C_BLOCK_BROKEN) { ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^375 /* Convert old I2C block commands to the new 376 convention. This preserves binary compatibility. */ 377 size = I2C_SMBUS_I2C_BLOCK_DATA; 378 if (read_write == I2C_SMBUS_READ) 379 temp.block[0] = I2C_SMBUS_BLOCK_MAX; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Except for size BROKEN
380 } 381 res = i2c_smbus_xfer(client->adapter, client->addr, client->flags, 382 read_write, command, size, &temp); ^^^^^ 383 if (!res && ((size == I2C_SMBUS_PROC_CALL) || 384 (size == I2C_SMBUS_BLOCK_PROC_CALL) || 385 (read_write == I2C_SMBUS_READ))) { 386 if (copy_to_user(data, &temp, datasize)) 387 return -EFAULT; 388 }Quoted 3 lines
The rest of the call tree seems straight forward but it's possible I have missed somewhere that checks data[0]. Here is how
ft260_smbus_xfer()looks like.
Quoted 7 lines
Oh, you are right. Despite that the SMbus block transaction limits the maximum number of bytes to 32, nothing prevents a user from specifying via ioctl a larger data size than the ft260 can handle in a single transfer.
I am going to fix it in the
ft260_smbus_write(with your Signed-off-by), but perhaps we should fix it in the first place, in thei2cdev_ioctl_smbusroutine? What do you think?
Could you just give me a Reported-by tag? Thanks!
regards,
dan carpenter
Quoted 6 lines · Dan Carpenter
Quoted 5 lines · Michael Zaidman
Oh, you are right. Despite that the SMbus block transaction limits the maximum number of bytes to 32, nothing prevents a user from specifying via ioctl a larger data size than the ft260 can handle in a single transfer.
Quoted 8 lines
Quoted 3 lines
I am going to fix it in the
ft260_smbus_write(with your Signed-off-by), but perhaps we should fix it in the first place, in thei2cdev_ioctl_smbusroutine? What do you think?Could you just give me a Reported-by tag? Thanks!
regards,
dan carpenter
Done, thanks!