bcm_qspi_mspi_exec_mem_op() builds a local command buffer cmd[6] holding one opcode byte, up to four address bytes and one spare byte, and sets t[0].len = op->addr.nbytes + op->dummy.nbytes + 1. bcm_qspi_exec_mem_op() only validates op->addr.nbytes <= 4 and never bounds op->dummy.nbytes, which spi_mem_check_op() also leaves unrestricted. With addr.nbytes = 4 and dummy.nbytes >= 2 the length becomes 7 or more, so write_to_hw() reads past cmd[] on the kernel stack and pushes the leaked bytes into the hardware TXRAM. Reject operations whose dummy phase does not fit the remaining byte of cmd[] by requiring op->dummy.nbytes <= 1, so such transfers fall back to the generic SPI path instead of overrunning the buffer. Reviewed-by: Guanglei Zhu Fixes: 5f195ee7d830c ("spi: bcm-qspi: Implement the spi_mem interface") Cc: stable@vger.kernel.org # 4.18+ Signed-off-by: Weibin Liu --- drivers/spi/spi-bcm-qspi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/spi/spi-bcm-qspi.c b/drivers/spi/spi-bcm-qspi.c index 0f96ac59da11..5031b2142479 100644 --- a/drivers/spi/spi-bcm-qspi.c +++ b/drivers/spi/spi-bcm-qspi.c @@ -1197,8 +1197,9 @@ static int bcm_qspi_exec_mem_op(struct spi_mem *mem, u32 addr = 0, len; u_char *buf; + /* cmd[] holds 1 opcode + 4 address + 1 dummy byte at most */ if (!op->data.nbytes || !op->addr.nbytes || op->addr.nbytes > 4 || - op->data.dir != SPI_MEM_DATA_IN) + op->dummy.nbytes > 1 || op->data.dir != SPI_MEM_DATA_IN) return -EOPNOTSUPP; buf = op->data.buf.in; --- base-commit: 24a19b953e2a3d0ea5a8c4951a0ab8f32720c907 change-id: 20261015-bcm-qspi-dummy-bytes-e0266f29d436 Best regards, -- Weibin Liu