dmaengine: dma-jz4780: fix NULL dereference in tx_status - #18
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jz4780_dma_tx_status() dereferences jzchan->desc->vdesc.tx.cookie without checking jzchan->desc. When the status of a completed transfer is queried after the channel finished (or was terminated) and no descriptor is active, jzchan->desc is NULL and the comparison faults. Reproduced on JZ4770 (RG350P handheld): querying residue from the MMC path after a completed transfer races the completion handler clearing jzchan->desc. Check jzchan->desc before comparing the cookie; with no active descriptor the residue lookup falls through to the default (0), which is correct for a completed transfer. Signed-off-by: wormuz <3341798+wormuz@users.noreply.github.com>
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jz4780_dma_tx_status() dereferences jzchan->desc->vdesc.tx.cookie without checking jzchan->desc. A status query racing the completion handler (which clears jzchan->desc) faults.
Reproduced on an RG350P handheld (JZ4770) via the MMC path querying residue after a completed transfer.