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drm/xe/vm: move xa_alloc to prevent UAF

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[ Upstream commit 74231870cf ]

Evil user can guess the next id of the vm before the ioctl completes and
then call vm destroy ioctl to trigger UAF since create ioctl is still
referencing the same vm. Move the xa_alloc all the way to the end to
prevent this.

v2:
 - Rebase

Fixes: dd08ebf6c3 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org> # v6.8+
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240925071426.144015-3-matthew.auld@intel.com
(cherry picked from commit dcfd397132)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Matthew Auld
2024-09-25 08:14:27 +01:00
committed by Greg Kroah-Hartman
parent 46b472a46c
commit 09cf8901fc
1 changed files with 8 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/gpu/drm/xe/xe_vm.c
+8 -8
View File
@@ -1905,10 +1905,6 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
if (IS_ERR(vm))
return PTR_ERR(vm);
err = xa_alloc(&xef->vm.xa, &id, vm, xa_limit_32b, GFP_KERNEL);
if (err)
goto err_close_and_put;
if (xe->info.has_asid) {
mutex_lock(&xe->usm.lock);
err = xa_alloc_cyclic(&xe->usm.asid_to_vm, &asid, vm,
@@ -1916,12 +1912,11 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
&xe->usm.next_asid, GFP_KERNEL);
mutex_unlock(&xe->usm.lock);
if (err < 0)
goto err_free_id;
goto err_close_and_put;
vm->usm.asid = asid;
}
args->vm_id = id;
vm->xef = xe_file_get(xef);
/* Record BO memory for VM pagetable created against client */
@@ -1934,10 +1929,15 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data,
args->reserved[0] = xe_bo_main_addr(vm->pt_root[0]->bo, XE_PAGE_SIZE);
#endif
/* user id alloc must always be last in ioctl to prevent UAF */
err = xa_alloc(&xef->vm.xa, &id, vm, xa_limit_32b, GFP_KERNEL);
if (err)
goto err_close_and_put;
args->vm_id = id;
return 0;
err_free_id:
xa_erase(&xef->vm.xa, id);
err_close_and_put:
xe_vm_close_and_put(vm);