In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: xsk: Fix DMA and xdp_frame leak on XDP_TX xmit failure
In the XSK branch of mlx5e_xmit_xdp_buff(), when sq->xmit_xdp_frame() returns false (e.g. XDPSQ is full), the function returns without unmapping the DMA address or freeing the xdp_frame allocated by xdp_convert_zc_to_xdp_frame(). The xdpi_fifo push only happens on success, so the completion path cannot recover these entries.
With CONFIG_DMA_API_DEBUG=y, the leak surfaces on driver unbind:
DMA-API: pci 0000:08:00.0: device driver has pending DMA allocations while released from device [count=1116] One of leaked entries details: [device address=0x000000010ffd7028] [size=1534 bytes] [mapped with DMA_TO_DEVICE] [mapped as phy] WARNING: kernel/dma/debug.c:881 at dma_debug_device_change+0x127/0x180 ... DMA-API: Mapped at: debug_dma_map_phys+0x4b/0xd0 dma_map_phys+0xfd/0x2d0 mlx5e_xdp_handle+0x5ae/0xac0 [mlx5_core] mlx5e_xsk_skb_from_cqe_mpwrq_linear+0xc4/0x170 [mlx5_core] mlx5e_handle_rx_cqe_mpwrq+0xc1/0x290 [mlx5_core]
Add the missing unmap + xdp_return_frame, matching the cleanup already done in mlx5e_xdp_xmit(). has_frags is rejected earlier in this branch, so no per-frag unmap is needed.