drm/nouveau: fix a use-after-free in nouveau_gem_prime_import_sg_table()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: drm/nouveau: fix a use-after-free in nouveau_gem_prime_import_sg_table() nouveau_bo_init() is backed by ttm_bo_init() and ferries its return code back to the caller. On failures, ttm will call nouveau_bo_del_ttm() and free the memory.Thus, when nouveau_bo_init() returns an error, the gem object has already been released. Then the call to nouveau_bo_ref() will use the freed "nvbo->bo" and lead to a use-after-free bug. We should delete the call to nouveau_bo_ref() to avoid the use-after-free.

References

• https://git.kernel.org/stable/c/56ee9577915dc06f55309901012a9ef68dbdb5a8
• https://git.kernel.org/stable/c/5d6093c49c098d86c7b136aba9922df44aeb6944
• https://git.kernel.org/stable/c/861f085f81fd569b02cc2c11165a9e6cca144424
• https://git.kernel.org/stable/c/3aeda2fe6517cc52663d4ce3588dd43f0d4124a7
• https://git.kernel.org/stable/c/7d80473e9f12548ac05b36af4fb9ce80f2f73509
• https://git.kernel.org/stable/c/540dfd188ea2940582841c1c220bd035a7db0e51