[PATCH 2/2] spi: spi-zynq-qspi: Fix stack violation bug

[Amit Kumar Mahapatra]

From: Karen Dombroski <karen.dombroski at marsbioimaging.com>

When the number of bytes for the op is greater than one, the read could
run off the end of the function stack and cause a crash.

This patch restores the behaviour of safely reading out of the original
opcode location.

Kernel panic - not syncing: stack-protector: Kernel stack is corrupted
 in: zynq_qspi_exec_mem_op+0x1c0/0x2e0
CPU1: stopping
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.9.11-mars-2020.11 #2
Hardware name: Xilinx Zynq Platform
[<c010c15c>] (unwind_backtrace) from [<c0109034>] (show_stack+0x10/0x14)
[<c0109034>] (show_stack) from [<c0591848>] (dump_stack+0xb8/0xd4)
[<c0591848>] (dump_stack) from [<c010aecc>] (handle_IPI+0xe0/0x1a4)
[<c010aecc>] (handle_IPI) from [<c0343890>] (gic_handle_irq+0x84/0x90)
[<c0343890>] (gic_handle_irq) from [<c0100b0c>] (__irq_svc+0x6c/0xa8)
Exception stack(0xef087f58 to 0xef087fa0)
7f40:                                                       00000780 ef7e26f4
7f60: 00000000 c0114380 00000000 00000000 ef086000 c0903eec 00000002 ef087fb8
7f80: c0903f28 00000000 ffffffe8 ef087fa8 c0106824 c0106814 60000013 ffffffff
[<c0100b0c>] (__irq_svc) from [<c0106814>] (arch_cpu_idle+0x1c/0x38)
[<c0106814>] (arch_cpu_idle) from [<c0598d58>] (default_idle_call+0x20/0x28)
[<c0598d58>] (default_idle_call) from [<c013b744>] (do_idle+0x124/0x22c)
[<c013b744>] (do_idle) from [<c013b9bc>] (cpu_startup_entry+0x18/0x1c)
[<c013b9bc>] (cpu_startup_entry) from [<001014ac>] (0x1014ac)

Signed-off-by: Karen Dombroski <karen.dombroski at marsbioimaging.com>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra at xilinx.com>
---
 drivers/spi/spi-zynq-qspi.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-zynq-qspi.c b/drivers/spi/spi-zynq-qspi.c
index 1acde9e24973..5a3d81c31d04 100644
--- a/drivers/spi/spi-zynq-qspi.c
+++ b/drivers/spi/spi-zynq-qspi.c
@@ -528,18 +528,17 @@ static int zynq_qspi_exec_mem_op(struct spi_mem *mem,
        struct zynq_qspi *xqspi = spi_controller_get_devdata(mem->spi->master);
        int err = 0, i;
        u8 *tmpbuf;
-       u8 opcode = op->cmd.opcode;

        dev_dbg(xqspi->dev, "cmd:%#x mode:%d.%d.%d.%d\n",
-               opcode, op->cmd.buswidth, op->addr.buswidth,
+               op->cmd.opcode, op->cmd.buswidth, op->addr.buswidth,
                op->dummy.buswidth, op->data.buswidth);

        zynq_qspi_chipselect(mem->spi, true);
        zynq_qspi_config_op(xqspi, mem->spi);

-       if (op->cmd.nbytes) {
+       if (op->cmd.opcode) {
                reinit_completion(&xqspi->data_completion);
-               xqspi->txbuf = &opcode;
+               xqspi->txbuf = (u8 *)&op->cmd.opcode;
                xqspi->rxbuf = NULL;
                xqspi->tx_bytes = op->cmd.nbytes;
                xqspi->rx_bytes = op->cmd.nbytes;
--
2.17.1

This email and any attachments are intended for the sole use of the named recipient(s) and contain(s) confidential information that may be proprietary, privileged or copyrighted under applicable law. If you are not the intended recipient, do not read, copy, or forward this email message or any attachments. Delete this email message and any attachments immediately.