spi: zynq-qspi: fix address buffer corruption and support 4-byte address

In zynq_qspi_exec_mem_op(), when transmitting address bytes, the driver
iterates over op->addr.nbytes and populates xqspi->txbuf[i]. However,
xqspi->txbuf is never re-assigned before populating the address, meaning
it still points to (u8 *)&op->cmd.opcode from the command phase.

This causes two severe issues:
1. Memory corruption: Writing into xqspi->txbuf writes past the opcode
   buffer on the stack (which was passed as const struct spi_mem_op *).
   If opcode is zero, xqspi->txbuf is uninitialized.
2. In zynq_qspi_supports_op(), operations with op->addr.nbytes > 3 are
   rejected. When paired with SPI NOR flashes larger than 16MB (such as
   Winbond W25Q256), spi_nor_spimem_check_read_pp_op() tests 4-byte address
   support, which fails and causes spi_nor_select_read() to drop all read
   capabilities, failing probe with -EINVAL (-22).

The Zynq-7000 QSPI controller hardware in manual I/O mode natively supports
transmitting 1 to 4 address bytes via its TXD FIFO registers
(ZYNQ_QSPI_TXD_00_00_OFFSET).

Fix this by introducing a local opaddr[4] buffer in zynq_qspi_exec_mem_op()
and explicitly setting xqspi->txbuf = opaddr before populating address
bytes. Also allow up to 4 address bytes in zynq_qspi_supports_op().

Fixes: 67dca5e580f1 ("spi: spi-mem: Add support for Zynq QSPI controller")
Cc: stable@vger.kernel.org
Signed-off-by: Pufan Jin <cyan2254650260@gmail.com>
Link: https://patch.msgid.link/20261016130812.282624-1-cyan2254650260@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

0 files changed, 0 insertions, 0 deletions