CVE-2026-64328

In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: f_fs: Fix DMA fence leak

In ffs_dmabuf_transfer(), a ffs_dma_fence object is kmalloc'd, with the

underlying dma_fence later initialized by dma_fence_init(), which sets

its kref counter to 1. Then, dma_resv_add_fence() gets a second

reference, and a pointer to the ffs_dma_fence is passed as the

usb_request's "context" field.

The dma-resv mechanism will manage the second reference, but the first

reference is never properly released; the ffs_dmabuf_cleanup() function

decreases the reference count, but only to balance with the reference

grab in ffs_dmabuf_signal_done().

The code will then slowly leak memory as more ffs_dma_fence objects are

created without being ever freed.

Address this issue by transferring ownership of the fence to the DMA

reservation object, by calling dma_fence_put() right after

dma_resv_add_fence(). The ffs_dma_fence then gets properly discarded

after being signalled.