unimore/kernel-hacking-2024-linux-steffo
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drm/vmwgfx: Stop accessing buffer objects which failed init

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ttm_bo_init_reserved on failure puts the buffer object back which
causes it to be deleted, but kfree was still being called on the same
buffer in vmw_bo_create leading to a double free.

After the double free the vmw_gem_object_create_with_handle was
setting the gem function objects before checking the return status
of vmw_bo_create leading to null pointer access.

Fix the entire path by relaying on ttm_bo_init_reserved to delete the
buffer objects on failure and making sure the return status is checked
before setting the gem function objects on the buffer object.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Fixes: 8afa13a058 ("drm/vmwgfx: Implement DRIVER_GEM")
Reviewed-by: Maaz Mombasawala <mombasawalam@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230208180050.2093426-1-zack@kde.org
(cherry picked from commit 36d421e632)
Cc: <stable@vger.kernel.org> # v5.17+
This commit is contained in:
Zack Rusin 2023-02-08 13:00:50 -05:00
parent bb2ff6c27b
commit 1a6897921f
2 changed files with 5 additions and 3 deletions
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4
drivers/gpu/drm/vmwgfx/vmwgfx_bo.c
View file

@ -462,6 +462,9 @@ int vmw_bo_create(struct vmw_private *vmw,
return -ENOMEM;
}
/*
* vmw_bo_init will delete the *p_bo object if it fails
*/
ret = vmw_bo_init(vmw, *p_bo, size,
placement, interruptible, pin,
bo_free);
@ -470,7 +473,6 @@ int vmw_bo_create(struct vmw_private *vmw,
return ret;
out_error:
kfree(*p_bo);
*p_bo = NULL;
return ret;
}

4
drivers/gpu/drm/vmwgfx/vmwgfx_gem.c
View file

@ -146,11 +146,11 @@ int vmw_gem_object_create_with_handle(struct vmw_private *dev_priv,
&vmw_sys_placement :
&vmw_vram_sys_placement,
true, false, &vmw_gem_destroy, p_vbo);
(*p_vbo)->base.base.funcs = &vmw_gem_object_funcs;
if (ret != 0)
goto out_no_bo;
(*p_vbo)->base.base.funcs = &vmw_gem_object_funcs;
ret = drm_gem_handle_create(filp, &(*p_vbo)->base.base, handle);
/* drop reference from allocate - handle holds it now */
drm_gem_object_put(&(*p_vbo)->base.base);