Patch "drm/amdkfd: fix potential kgd_mem UAFs" has been added to the 6.2-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amdkfd: fix potential kgd_mem UAFs

to the 6.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amdkfd-fix-potential-kgd_mem-uafs.patch
and it can be found in the queue-6.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a22bb3b87b6c0bdc68489a8b0fcde65f0449e650
Author: Chia-I Wu <olvaffe@xxxxxxxxx>
Date:   Wed Mar 8 13:37:24 2023 -0800

    drm/amdkfd: fix potential kgd_mem UAFs
    
    [ Upstream commit 9da050b0d9e04439d225a2ec3044af70cdfb3933 ]
    
    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@xxxxxxxxx>
    Signed-off-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
    Reviewed-by: Felix Kuehling <Felix.Kuehling@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
index f79b8e964140e..e191d38f3da62 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_chardev.c
@@ -1298,14 +1298,14 @@ 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]);
@@ -1321,9 +1321,9 @@ static int kfd_ioctl_map_memory_to_gpu(struct file *filep,
 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;
@@ -1337,6 +1337,7 @@ 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");
@@ -1389,16 +1390,19 @@ 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]);
@@ -1414,9 +1418,9 @@ 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;
 }