From: Lv Yunlong lyl2019@mail.ustc.edu.cn
commit ea995218dddba171fecd05496c69617c5ef3c5b8 upstream.
Our code analyzer reported a double free bug.
In gen8_preallocate_top_level_pdp, pde and pde->pt.base are allocated via alloc_pd(vm) with one reference. If pin_pt_dma() failed, pde->pt.base is freed by i915_gem_object_put() with a reference dropped. Then free_pd calls free_px() defined in intel_ppgtt.c, which calls i915_gem_object_put() to put pde->pt.base again.
As pde->pt.base is protected by refcount, so the second put will not free pde->pt.base actually. But, maybe it is better to remove the first put?
Fixes: 82adf901138cc ("drm/i915/gt: Shrink i915_page_directory's slab bucket") Signed-off-by: Lv Yunlong lyl2019@mail.ustc.edu.cn Reviewed-by: Matthew Auld matthew.auld@intel.com Signed-off-by: Matthew Auld matthew.auld@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20210426124340.4238-1-lyl2019@... (cherry picked from commit ac69496fe65cca0611d5917b7d232730ff605bc7) Signed-off-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/i915/gt/gen8_ppgtt.c | 1 - 1 file changed, 1 deletion(-)
--- a/drivers/gpu/drm/i915/gt/gen8_ppgtt.c +++ b/drivers/gpu/drm/i915/gt/gen8_ppgtt.c @@ -630,7 +630,6 @@ static int gen8_preallocate_top_level_pd
err = pin_pt_dma(vm, pde->pt.base); if (err) { - i915_gem_object_put(pde->pt.base); free_pd(vm, pde); return err; }