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Date: Tue, 25 Aug 2020 16:13:58 +0300 From: Stanimir Varbanov <stanimir.varbanov@...aro.org> To: Mansur Alisha Shaik <mansur@...eaurora.org>, linux-media@...r.kernel.org, stanimir.varbanov@...aro.org Cc: linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, vgarodia@...eaurora.org Subject: Re: [RESEND 3/3] venus: handle use after free for iommu_map/iommu_unmap 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 > 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@...eaurora.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) { why not just ? if (iommu) > + iommu_domain_free(iommu); > + core->fw.iommu_domain = NULL; > + } > > platform_device_unregister(to_platform_device(core->fw.dev)); > } > -- regards, Stan
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