tcp: prevent collapsing skbs across boundary in rtx queue

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98549
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:06 UTC
Updated2026-10-21 13:21:32 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: tcp: prevent collapsing skbs across boundary in rtx queue tcp_write_collapse_fence() sets TCP_SKB_CB(skb)->eor = 1 on tcp_write_queue_tail(sk) to prevent skbs queued after a switch to device encryption from being collapsed into earlier skbs. The fence is a no-op if all earlier data has already been transmitted when the switch happens: sk->sk_write_queue is empty. The not yet acknowledged earlier skbs wait in sk->tcp_rtx_queue with eor 0. On a subsequent retransmit or SACK shift, tcp_retrans_try_collapse() or tcp_shift_skb_data() can then merge an skb queued after the switch into one queued before it. Both users of the fence are affected: - psp: devices only encrypt skbs with skb->decrypted set. The merged skb keeps decrypted = 0 from the earlier skb, so merged data sent after psp_sock_assoc_set_tx() is retransmitted in cleartext. - tls device offload: the merged skb straddles the start marker set in tls_set_device_offload(). The software fallback (fill_sg_in() returns -EINVAL) and the mlx5, nfp and funeth drivers cannot handle such an skb and drop it. Every retransmit rebuilds the same skb, so the connection stalls. Fix this in two places, for defense in depth: 1. Fall back to tcp_rtx_queue_tail(sk) in tcp_write_collapse_fence() when tcp_write_queue_tail(sk) is NULL. 2. Check !skb_cmp_decrypted(to, from) in tcp_skb_can_collapse(), as tcp_skb_can_collapse_rx() does on receive. skb_shift(), which both collapse paths call, already has a DEBUG_NET_WARN_ON_ONCE() for this condition.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected e8f69799810c32dd40c6724d829eccc70baad07f 9e2a2f98e8c0197108c6d97a1fa43bfd89071c30 git Not specified
CNA Linux Linux affected e8f69799810c32dd40c6724d829eccc70baad07f 1ae7aee395245874d797890380d9192bd858fb7e git Not specified
CNA Linux Linux affected e8f69799810c32dd40c6724d829eccc70baad07f 7ba87509c54cd519e7ed362e0c85e8431f066a18 git Not specified
CNA Linux Linux affected e8f69799810c32dd40c6724d829eccc70baad07f 08e835f5ec6e261c79d8c39f8618b3af29e3b0da git Not specified
CNA Linux Linux affected e8f69799810c32dd40c6724d829eccc70baad07f fc6d80eb504458d6416b75a94188b268c95c6533 git Not specified
CNA Linux Linux affected 4.18 Not specified
CNA Linux Linux unaffected 4.18 semver Not specified
CNA Linux Linux unaffected 6.6.160 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.112 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.55 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.9 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/1ae7aee395245874d797890380d9192bd858fb7e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9e2a2f98e8c0197108c6d97a1fa43bfd89071c30 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fc6d80eb504458d6416b75a94188b268c95c6533 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/08e835f5ec6e261c79d8c39f8618b3af29e3b0da 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7ba87509c54cd519e7ed362e0c85e8431f066a18 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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