Bug 2554985 (CVE-2026-98592) - CVE-2026-98592 kernel: net: spacemit: clear TX descriptor on fragment mapping failure
Summary: CVE-2026-98592 kernel: net: spacemit: clear TX descriptor on fragment mapping...
Keywords:
Status: NEW
Alias: CVE-2026-98592
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-10-18 15:37 UTC by OSIDB Bzimport
Modified: 2026-10-20 04:29 UTC (History)
17 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-10-18 15:37:30 UTC
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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