7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Weibin Liu [ Upstream commit 9e44f0df3fff215d9033089e85980048c3ac132a ] 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 Link: https://patch.msgid.link/20261015-bcm-qspi-dummy-bytes-v1-1-c319da3c2497@xiaopeng.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- 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 0f96ac59da114..5031b21424795 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; -- 2.53.0