CVE-2026-98592 in Linux
Résumé
par MITRE • 18/10/2026
In the Linux kernel, the following vulnerability has been resolved:
net: spacemit: clear TX descriptor on fragment mapping failure
emac_tx_mem_map() writes TX_DESC_0_OWN into the ring descriptor for every slot beyond old_head as soon as that slot's memset()'d local copy is committed with "*tx_desc_addr = tx_desc", i.e. before the buffers for that slot have necessarily all been mapped successfully. If emac_tx_map_frag() then fails on a later fragment, the err_free_skb path calls emac_free_tx_buf() to unmap and drop the skb, but leaves the already-written descriptor memory untouched, and tx_ring->head is never advanced past old_head (the "tx_ring->head = head" store is skipped by the goto).
So a slot between old_head and the rolled-back head can be left with TX_DESC_0_OWN set and buffer_addr_{1,2} pointing at DMA mappings that
emac_free_tx_buf() just tore down, while software considers that slot free again. The next successful emac_tx_mem_map() call only rebuilds old_head itself; if the DMA engine auto-advances into the following descriptor once it finishes old_head's packet, it will fetch that stale, already-unmapped address.
emac_tx_clean_desc() already treats emac_free_tx_buf() and clearing the descriptor as a pair when reclaiming completed descriptors; do the same in the mapping failure path.
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