Re: [RESEND 3/3] venus: handle use after free for iommu_map/iommu_unmap

Stanimir Varbanov
2020-08-10T09:53:34Z

Hi,

On 8/7/20 9:24 AM, Mansur Alisha Shaik wrote:
> In concurrency usecase and reboot scenario we are trying
> to map fw.iommu_domain which is already unmapped during

I guess you want to say "to unmap iommu domain which is already unmapped" ?

> shutdown. This is causing NULL pointer dereference crash.
>
> This case is handled by adding necessary checks.
>
> Call trace:
> __iommu_map+0x4c/0x348
> iommu_map+0x5c/0x70
> venus_boot+0x184/0x230 [venus_core]
> venus_sys_error_handler+0xa0/0x14c [venus_core]
> process_one_work+0x210/0x3d0
> worker_thread+0x248/0x3f4
> kthread+0x11c/0x12c
> ret_from_fork+0x10/0x18
>
> Signed-off-by: Mansur Alisha Shaik <mansur@codeaurora.org>
> ---
> drivers/media/platform/qcom/venus/firmware.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/media/platform/qcom/venus/firmware.c b/drivers/media/platform/qcom/venus/firmware.c
> index 8801a6a..c427e88 100644
> --- a/drivers/media/platform/qcom/venus/firmware.c
> +++ b/drivers/media/platform/qcom/venus/firmware.c
> @@ -171,9 +171,14 @@ static int venus_shutdown_no_tz(struct venus_core *core)
>
> iommu = core->fw.iommu_domain;
>
> - unmapped = iommu_unmap(iommu, VENUS_FW_START_ADDR, mapped);
> - if (unmapped != mapped)
> - dev_err(dev, "failed to unmap firmware\n");
> + if (core->fw.mapped_mem_size && iommu) {
> + unmapped = iommu_unmap(iommu, VENUS_FW_START_ADDR, mapped);
> +
> + if (unmapped != mapped)
> + dev_err(dev, "failed to unmap firmware\n");
> + else
> + core->fw.mapped_mem_size = 0;
> + }
>
> return 0;
> }
> @@ -288,7 +293,11 @@ void venus_firmware_deinit(struct venus_core *core)
> iommu = core->fw.iommu_domain;
>
> iommu_detach_device(iommu, core->fw.dev);
> - iommu_domain_free(iommu);
> +
> + if (core->fw.iommu_domain) {
> + iommu_domain_free(iommu);
> + core->fw.iommu_domain = NULL;
> + }
>
> platform_device_unregister(to_platform_device(core->fw.dev));
> }
>

--
regards,
Stan