dmaengine: sun6i: fix undefined behaviour in sun6i_dma_tx_status

sun6i_dma_tx_status() calls vchan_find_desc() to look up the virtual
descriptor for a given cookie, before checking whether the pointer
vd is NULL:

    vd = vchan_find_desc(&vchan->vc, cookie);
    txd = to_sun6i_desc(&vd->tx);   /* vd may be NULL here */

    if (vd) {
        for (lli = txd->v_lli; ...)

vchan_find_desc() returns NULL when the descriptor has already been
completed or is in-flight on a physical channel and no longer present
in the virtual channel's descriptor list. When vd is NULL,
to_sun6i_desc() is called unconditionally on &vd->tx before the NULL
check, which is undefined behaviour. Move the call inside the if (vd)
guard to ensure it is only reached with a valid pointer.

    vd = vchan_find_desc(&vchan->vc, cookie);
    if (vd) {
        struct sun6i_desc *txd = to_sun6i_desc(&vd->tx);
        for (lli = txd->v_lli; ...)

Fixes: 555859308723 ("dmaengine: sun6i: Add driver for the Allwinner A31 DMA controller")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-sonnet-4-6
Signed-off-by: Christian Lugnberg <christian.lugnberg@soundtrack.io>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260817135723.12807-3-christian.lugnberg@soundtrack.io
Signed-off-by: Vinod Koul <vkoul@kernel.org>

0 files changed, 0 insertions, 0 deletions