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
On Fri, Apr 09, 2021 at 03:32:06PM +0300, Dan Carpenter wrote: > 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. 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 > > 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
On Sat, Apr 10, 2021 at 03:27:29PM +0300, Michael Zaidman wrote:
> On Fri, Apr 09, 2021 at 03:32:06PM +0300, Dan Carpenter wrote:
> > 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.
>
> 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.
>
> >
> > 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
On Sat, Apr 10, 2021 at 06:37:13PM +0300, Dan Carpenter wrote: > On Sat, Apr 10, 2021 at 03:27:29PM +0300, Michael Zaidman wrote: > > On Fri, Apr 09, 2021 at 03:32:06PM +0300, Dan Carpenter wrote: > > > 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. > > > > 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. > > > > > > > > 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. 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? > > 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 > >
On Sun, Apr 11, 2021 at 12:04:25AM +0300, Michael Zaidman wrote:
> On Sat, Apr 10, 2021 at 06:37:13PM +0300, Dan Carpenter wrote:
> > On Sat, Apr 10, 2021 at 03:27:29PM +0300, Michael Zaidman wrote:
> > > On Fri, Apr 09, 2021 at 03:32:06PM +0300, Dan Carpenter wrote:
> > > > 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.
> > >
> > > 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.
> > >
> > > >
> > > > 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.
>
> 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?
Could you just give me a Reported-by tag? Thanks!
regards,
dan carpenter
On Mon, Apr 12, 2021 at 12:11:51PM +0300, Dan Carpenter wrote:
> On Sun, Apr 11, 2021 at 12:04:25AM +0300, Michael Zaidman wrote:
> >
> > 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?
>
> Could you just give me a Reported-by tag? Thanks!
>
> regards,
> dan carpenter
Done, thanks!