Unverified Commit 1417927d authored by Christophe Leroy's avatar Christophe Leroy Committed by Mark Brown
Browse files

spi: fsl-cpm: Check length parity before switching to 16 bit mode 

Commit fc96ec82 ("spi: fsl-cpm: Use 16 bit mode for large transfers
with even size") failed to make sure that the size is really even
before switching to 16 bit mode. Until recently the problem went
unnoticed because kernfs uses a pre-allocated bounce buffer of size
PAGE_SIZE for reading EEPROM.

But commit 8ad6249c ("eeprom: at25: convert to spi-mem API")
introduced an additional dynamically allocated bounce buffer whose size
is exactly the size of the transfer, leading to a buffer overrun in
the fsl-cpm driver when that size is odd.

Add the missing length parity verification and remain in 8 bit mode
when the length is not even.

Fixes: fc96ec82 ("spi: fsl-cpm: Use 16 bit mode for large transfers with even size")
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/all/638496dd-ec60-4e53-bad7-eb657f67d580@csgroup.eu/


Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: default avatarSverdlin Alexander <alexander.sverdlin@siemens.com>
Link: https://patch.msgid.link/3c4d81c3923c93f95ec56702a454744a4bad3cfc.1763627618.git.christophe.leroy@csgroup.eu


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent a8a31361

drivers/spi/spi-fsl-spi.c

+1 −1
Original line number Diff line number Diff line
@@ -335,7 +335,7 @@ static int fsl_spi_prepare_message(struct spi_controller *ctlr, 
			if (t->bits_per_word == 16 || t->bits_per_word == 32)

				t->bits_per_word = 8; /* pretend its 8 bits */

			if (t->bits_per_word == 8 && t->len >= 256 &&

			    (mpc8xxx_spi->flags & SPI_CPM1))

			    !(t->len & 1) && (mpc8xxx_spi->flags & SPI_CPM1))

				t->bits_per_word = 16;

		}

	}