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CVE-2026-68136

net: gro: fix double aggregation of flush-marked skbs

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.266, 6.1.184, 6.6.153, 6.12.101, 6.18.42, and 1 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: total

Summary

In the Linux kernel, the following vulnerability has been resolved: net: gro: fix double aggregation of flush-marked skbs Commit 0ab03f353d36 ("net-gro: Fix GRO flush when receiving a GSO packet.") added a flush check to skb_gro_receive(), but skb_gro_receive_list() lacks the same validation. As a result, packets marked with NAPI_GRO_CB(skb)->flush may still be re-aggregated. This allows already-GRO'd packets with existing frag_list to be re-aggregated into a new GRO session, corrupting the frag_list chain structure. When skb_segment() attempts to unpack these malformed packets, it encounters invalid state and triggers a kernel panic. Scenario (Tethering/Device forwarding): 1. Driver: Generated aggregated packet P1 via LRO with frag_list 2. Dev A: Receives aggregated fraglist packet and flush flag set 3. Dev A: Re-enters GRO, skb_gro_receive_list() is called 4. Missing flush check allows re-aggregation despite flush flag 5. Frag_list chain becomes corrupted (loops or dangling refs) 6. Dev B: TX path calls skb_segment(), crashes on corrupted frag_list Root cause in skb_segment(): The check at line ~4891: if (hsize <= 0 && i >= nfrags && skb_headlen(list_skb) && (skb_headlen(list_skb) == len || sg)) { When frag_list is corrupted by double aggregation, when list_skb is a NULL pointer from skb->next, skb_headlen(list_skb) dereference NULL/corrupted pointers occurs. Call Trace: skb_headlen(NULL skb) skb_segment tcp_gso_segment tcp4_gso_segment inet_gso_segment skb_mac_gso_segment __skb_gso_segment skb_gso_segment validate_xmit_skb validate_xmit_skb_list sch_direct_xmit qdisc_restart __qdisc_run qdisc_run net_tx_action Fix: Add NAPI_GRO_CB(skb)->flush validation to the early-return check in skb_gro_receive_list(), matching the defensive programming pattern of skb_gro_receive().

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in 7fc7e35212cf58c134310fb47566a844297ceae9; From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in d1fb23f8f794ac4683127bd49a6422bd87e0ac02; From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in db3e82da616f52e2b27e25e7be3fde2f2a5e54d6; From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in 107e1a469f53a2a70874f3f12bf6fcd23925da1d; From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in a4dfd46cc8f08a29c6183794790547d0945f3d45; From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in fc0c0f7a207f0cd2d2aa725696c907f7d03af9e0; From 3a1296a38d0cf62bffb9a03c585cbd5dbf15d596 · fixed in e751256486d0ded20f5a9f9863467f1dce65142f

  • Linux Linux

    5.6

  • KernelLinux

    From 5.6.0 · fixed in 5.10.266; From 5.11.0 · fixed in 6.1.184; From 6.2.0 · fixed in 6.6.153; From 6.7.0 · fixed in 6.12.101; From 6.13.0 · fixed in 6.18.42; From 6.19.0 · fixed in 7.1.6

References 7

git.kernel.org