In the Linux kernel, the following vulnerability has been resolved: net: atlantic: Fix DMA mapping for PTP hwts ring Function aq_ring_hwts_rx_alloc() maps extra AQ_CFG_RXDS_DEF bytes for PTP HWTS ring but then generic aq_ring_free() does not take this into account. Create and use a specific function to free HWTS ring to fix this issue. Trace: [ 215.351607] ------------[ cut here ]------------ [ 215.351612] DMA-API: atlantic 0000:4b:00.0: device driver frees DMA memory with different size [device address=0x00000000fbdd0000] [map size=34816 bytes] [unmap size=32768 bytes] [ 215.351635] WARNING: CPU: 33 PID: 10759 at kernel/dma/debug.c:988 check_unmap+0xa6f/0x2360 ... [ 215.581176] Call Trace: [ 215.583632] <TASK> [ 215.585745] ? show_trace_log_lvl+0x1c4/0x2df [ 215.590114] ? show_trace_log_lvl+0x1c4/0x2df [ 215.594497] ? debug_dma_free_coherent+0x196/0x210 [ 215.599305] ? check_unmap+0xa6f/0x2360 [ 215.603147] ? __warn+0xca/0x1d0 [ 215.606391] ? check_unmap+0xa6f/0x2360 [ 215.610237] ? report_bug+0x1ef/0x370 [ 215.613921] ? handle_bug+0x3c/0x70 [ 215.617423] ? exc_invalid_op+0x14/0x50 [ 215.621269] ? asm_exc_invalid_op+0x16/0x20 [ 215.625480] ? check_unmap+0xa6f/0x2360 [ 215.629331] ? mark_lock.part.0+0xca/0xa40 [ 215.633445] debug_dma_free_coherent+0x196/0x210 [ 215.638079] ? __pfx_debug_dma_free_coherent+0x10/0x10 [ 215.643242] ? slab_free_freelist_hook+0x11d/0x1d0 [ 215.648060] dma_free_attrs+0x6d/0x130 [ 215.651834] aq_ring_free+0x193/0x290 [atlantic] [ 215.656487] aq_ptp_ring_free+0x67/0x110 [atlantic] ... [ 216.127540] ---[ end trace 6467e5964dd2640b ]--- [ 216.132160] DMA-API: Mapped at: [ 216.132162] debug_dma_alloc_coherent+0x66/0x2f0 [ 216.132165] dma_alloc_attrs+0xf5/0x1b0 [ 216.132168] aq_ring_hwts_rx_alloc+0x150/0x1f0 [atlantic] [ 216.132193] aq_ptp_ring_alloc+0x1bb/0x540 [atlantic] [ 216.132213] aq_nic_init+0x4a1/0x760 [atlantic]
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.