Re: [PATCH v4 01/14] dmaengine: tegra-apb: Fix use-after-free

Jon Hunter
2020-01-14T15:09:58Z

On 12/01/2020 17:29, Dmitry Osipenko wrote:
> I was doing some experiments with I2C and noticed that Tegra APB DMA
> driver crashes sometime after I2C DMA transfer termination. The crash
> happens because tegra_dma_terminate_all() bails out immediately if pending
> list is empty, thus it doesn't release the half-completed descriptors
> which are getting re-used before ISR tasklet kicks-in.

Can you elaborate a bit more on how these are getting re-used? What is
the sequence of events which results in the panic? I believe that this
was also reported in the past [0] and so I don't doubt there is an issue
here, but would like to completely understand this.

Thanks!
Jon

[0] https://lore.kernel.org/patchwork/patch/675349/

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