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

Mansur Alisha Shaik
2020-08-07T06:25:07Z

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@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));
}
--
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