diff options
| author | Rob Clark <[email protected]> | 2023-01-19 09:32:58 -0800 |
|---|---|---|
| committer | Rodrigo Vivi <[email protected]> | 2023-01-30 15:48:08 -0500 |
| commit | 41d419382ec7e257e54b7b6ff0d3623aafb1316d (patch) | |
| tree | b6cf4aff0a181e24eeb2994cfea2cd0c9c691cc0 | |
| parent | 6d796c50f84ca79f1722bb131799e5a5710c4700 (diff) | |
drm/i915: Avoid potential vm use-after-free
Adding the vm to the vm_xa table makes it visible to userspace, which
could try to race with us to close the vm. So we need to take our extra
reference before putting it in the table.
Signed-off-by: Rob Clark <[email protected]>
Reviewed-by: Matthew Auld <[email protected]>
Fixes: 9ec8795e7d91 ("drm/i915: Drop __rcu from gem_context->vm")
Cc: <[email protected]> # v5.16+
Signed-off-by: Tvrtko Ursulin <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
(cherry picked from commit 99343c46d4e2b34c285d3d5f68ff04274c2f9fb4)
Signed-off-by: Rodrigo Vivi <[email protected]>
| -rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_context.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index 6250de9b9196..e4b78ab4773b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -1861,11 +1861,19 @@ static int get_ppgtt(struct drm_i915_file_private *file_priv, vm = ctx->vm; GEM_BUG_ON(!vm); + /* + * Get a reference for the allocated handle. Once the handle is + * visible in the vm_xa table, userspace could try to close it + * from under our feet, so we need to hold the extra reference + * first. + */ + i915_vm_get(vm); + err = xa_alloc(&file_priv->vm_xa, &id, vm, xa_limit_32b, GFP_KERNEL); - if (err) + if (err) { + i915_vm_put(vm); return err; - - i915_vm_get(vm); + } GEM_BUG_ON(id == 0); /* reserved for invalid/unassigned ppgtt */ args->value = id; |