This is a note to let you know that I've just added the patch titled
drm/i915: Avoid potential vm use-after-free
to the 6.1-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-i915-avoid-potential-vm-use-after-free.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 41d419382ec7e257e54b7b6ff0d3623aafb1316d Mon Sep 17 00:00:00 2001
From: Rob Clark <robdclark@xxxxxxxxxxxx>
Date: Thu, 19 Jan 2023 09:32:58 -0800
Subject: drm/i915: Avoid potential vm use-after-free
From: Rob Clark <robdclark@xxxxxxxxxxxx>
commit 41d419382ec7e257e54b7b6ff0d3623aafb1316d upstream.
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 <robdclark@xxxxxxxxxxxx>
Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>
Fixes: 9ec8795e7d91 ("drm/i915: Drop __rcu from gem_context->vm")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.16+
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230119173321.2825472-1-robdclark@xxxxxxxxx
(cherry picked from commit 99343c46d4e2b34c285d3d5f68ff04274c2f9fb4)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_context.c | 14 +++++++++++---
1 file 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;
--
2.39.1
Patches currently in stable-queue which might be from robdclark@xxxxxxxxxxxx are
queue-6.1/drm-panel-boe-tv101wum-nl6-ensure-dsi-writes-succeed.patch
queue-6.1/drm-i915-avoid-potential-vm-use-after-free.patch
queue-6.1/drm-i915-fix-potential-bit_17-double-free.patch
