drm/amdkfd: fix potential kgd_mem UAFs

kgd_mem pointers returned by kfd_process_device_translate_handle are
only guaranteed to be valid while p->mutex is held. As soon as the mutex
is unlocked, another thread can free the BO.

Signed-off-by: Chia-I Wu <olvaffe@gmail.com>
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index a0e30f21e12e70a763b0a773895b20daee59b13a..de310ed367ca1dda7c41a437476cf1b70a345677 100644 (file)
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1312,14 +1312,14 @@ static int kfd_ioctl_map_memory_to_gpu(struct file *filep,
                args->n_success = i+1;
        }
 
-       mutex_unlock(&p->mutex);
-
        err = amdgpu_amdkfd_gpuvm_sync_memory(dev->adev, (struct kgd_mem *) mem, true);
        if (err) {
                pr_debug("Sync memory failed, wait interrupted by user signal\n");
                goto sync_memory_failed;
        }
 
+       mutex_unlock(&p->mutex);
+
        /* Flush TLBs after waiting for the page table updates to complete */
        for (i = 0; i < args->n_devices; i++) {
                peer_pdd = kfd_process_device_data_by_id(p, devices_arr[i]);
@@ -1335,9 +1335,9 @@ get_process_device_data_failed:
 bind_process_to_device_failed:
 get_mem_obj_from_handle_failed:
 map_memory_to_gpu_failed:
+sync_memory_failed:
        mutex_unlock(&p->mutex);
 copy_from_user_failed:
-sync_memory_failed:
        kfree(devices_arr);
 
        return err;
@@ -1351,6 +1351,7 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
        void *mem;
        long err = 0;
        uint32_t *devices_arr = NULL, i;
+       bool flush_tlb;
 
        if (!args->n_devices) {
                pr_debug("Device IDs array empty\n");
@@ -1403,16 +1404,19 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
                }
                args->n_success = i+1;
        }
-       mutex_unlock(&p->mutex);
 
-       if (kfd_flush_tlb_after_unmap(pdd->dev)) {
+       flush_tlb = kfd_flush_tlb_after_unmap(pdd->dev);
+       if (flush_tlb) {
                err = amdgpu_amdkfd_gpuvm_sync_memory(pdd->dev->adev,
                                (struct kgd_mem *) mem, true);
                if (err) {
                        pr_debug("Sync memory failed, wait interrupted by user signal\n");
                        goto sync_memory_failed;
                }
+       }
+       mutex_unlock(&p->mutex);
 
+       if (flush_tlb) {
                /* Flush TLBs after waiting for the page table updates to complete */
                for (i = 0; i < args->n_devices; i++) {
                        peer_pdd = kfd_process_device_data_by_id(p, devices_arr[i]);
@@ -1428,9 +1432,9 @@ static int kfd_ioctl_unmap_memory_from_gpu(struct file *filep,
 bind_process_to_device_failed:
 get_mem_obj_from_handle_failed:
 unmap_memory_from_gpu_failed:
+sync_memory_failed:
        mutex_unlock(&p->mutex);
 copy_from_user_failed:
-sync_memory_failed:
        kfree(devices_arr);
        return err;
 }