dma-buf/dma-resv: Stop leaking on krealloc() failure

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: dma-buf/dma-resv: Stop leaking on krealloc() failure Currently dma_resv_get_fences() will leak the previously allocated array if the fence iteration got restarted and the krealloc_array() fails. Free the old array by hand, and make sure we still clear the returned *fences so the caller won't end up accessing freed memory. Some (but not all) of the callers of dma_resv_get_fences() seem to still trawl through the array even when dma_resv_get_fences() failed. And let's zero out *num_fences as well for good measure.

References

• https://git.kernel.org/stable/c/19e7b9f1f7e1cb92a4cc53b4c064f7fb4b1f1983
• https://git.kernel.org/stable/c/819656cc03dec7f7f7800274dfbc8eb49f888e9f
• https://git.kernel.org/stable/c/05abb3be91d8788328231ee02973ab3d47f5e3d2