This is a note to let you know that I've just added the patch titled spi: spidev: fix possible arithmetic overflow for multi-transfer message to the 3.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: spi-spidev-fix-possible-arithmetic-overflow-for-multi-transfer-message.patch and it can be found in the queue-3.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From f20fbaad7620af2df36a1f9d1c9ecf48ead5b747 Mon Sep 17 00:00:00 2001 From: Ian Abbott <abbotti@xxxxxxxxx> Date: Mon, 23 Mar 2015 17:50:27 +0000 Subject: spi: spidev: fix possible arithmetic overflow for multi-transfer message From: Ian Abbott <abbotti@xxxxxxxxx> commit f20fbaad7620af2df36a1f9d1c9ecf48ead5b747 upstream. `spidev_message()` sums the lengths of the individual SPI transfers to determine the overall SPI message length. It restricts the total length, returning an error if too long, but it does not check for arithmetic overflow. For example, if the SPI message consisted of two transfers and the first has a length of 10 and the second has a length of (__u32)(-1), the total length would be seen as 9, even though the second transfer is actually very long. If the second transfer specifies a null `rx_buf` and a non-null `tx_buf`, the `copy_from_user()` could overrun the spidev's pre-allocated tx buffer before it reaches an invalid user memory address. Fix it by checking that neither the total nor the individual transfer lengths exceed the maximum allowed value. Thanks to Dan Carpenter for reporting the potential integer overflow. Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/spi/spidev.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/spi/spidev.c +++ b/drivers/spi/spidev.c @@ -243,7 +243,10 @@ static int spidev_message(struct spidev_ k_tmp->len = u_tmp->len; total += k_tmp->len; - if (total > bufsiz) { + /* Check total length of transfers. Also check each + * transfer length to avoid arithmetic overflow. + */ + if (total > bufsiz || k_tmp->len > bufsiz) { status = -EMSGSIZE; goto done; } Patches currently in stable-queue which might be from abbotti@xxxxxxxxx are queue-3.14/spi-spidev-fix-possible-arithmetic-overflow-for-multi-transfer-message.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html