6.6-stable review patch. If anyone has any objections, please let me know.
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From: Christophe Leroy christophe.leroy@csgroup.eu
commit 1417927df8049a0194933861e9b098669a95c762 upstream.
Commit fc96ec826bce ("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 8ad6249c51d0 ("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: fc96ec826bce ("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: Christophe Leroy christophe.leroy@csgroup.eu Reviewed-by: Sverdlin Alexander alexander.sverdlin@siemens.com Link: https://patch.msgid.link/3c4d81c3923c93f95ec56702a454744a4bad3cfc.1763627618... Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/spi/spi-fsl-spi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/spi/spi-fsl-spi.c +++ b/drivers/spi/spi-fsl-spi.c @@ -336,7 +336,7 @@ static int fsl_spi_prepare_message(struc 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; } }