[PATCH] spi-imx: prevent overflow when estimating transfer time

[PATCH] spi-imx: prevent overflow when estimating transfer time

[Antonio Quartulli]

The words delay is computed by multiplying two unsigned ints
and by adding up the result to a u64 variable.

The multiplication, however, is performed with 32bit math
thus losing data when the actual result is larger than UINT32_MAX.

Fix the operation by casting the first operand to u64, thus forcing
the multiplication to be performed with 64bit math.

This fixes 1 OVERFLOW_BEFORE_WIDEN issue reported by Coverity
Report: CID 1601859:  Integer handling issues  (OVERFLOW_BEFORE_WIDEN)

Cc: Mark Brown <broonie@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: imx@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Antonio Quartulli <antonio@mandelbit.com>
---
 drivers/spi/spi-imx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 0b6b0151b3a3..eeb7d082c247 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -1685,7 +1685,7 @@ static unsigned int spi_imx_transfer_estimate_time_us(struct spi_transfer *trans
 		words = DIV_ROUND_UP(transfer->len * BITS_PER_BYTE, transfer->bits_per_word);
 		word_delay_us = DIV_ROUND_CLOSEST(spi_delay_to_ns(&transfer->word_delay, transfer),
 						  NSEC_PER_USEC);
-		result += words * word_delay_us;
+		result += (u64)words * word_delay_us;
 	}
 
 	return min(result, U32_MAX);
-- 
2.45.2

Re: [PATCH] spi-imx: prevent overflow when estimating transfer time

[Mark Brown]

On Fri, 15 Nov 2024 23:02:02 +0100, Antonio Quartulli wrote:
> The words delay is computed by multiplying two unsigned ints
> and by adding up the result to a u64 variable.
> 
> The multiplication, however, is performed with 32bit math
> thus losing data when the actual result is larger than UINT32_MAX.
> 
> Fix the operation by casting the first operand to u64, thus forcing
> the multiplication to be performed with 64bit math.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi-imx: prevent overflow when estimating transfer time
      commit: 9e141955ede223d82251a59644ff9448a5aba580

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark