net: gso: fix panic on frag_list with mixed head alloc types

Description

In the Linux kernel, the following vulnerability has been resolved: net: gso: fix panic on frag_list with mixed head alloc types Since commit 3dcbdb134f32 ("net: gso: Fix skb_segment splat when splitting gso_size mangled skb having linear-headed frag_list"), it is allowed to change gso_size of a GRO packet. However, that commit assumes that "checking the first list_skb member suffices; i.e if either of the list_skb members have non head_frag head, then the first one has too". It turns out this assumption does not hold. We've seen BUG_ON being hit in skb_segment when skbs on the frag_list had differing head_frag with the vmxnet3 driver. This happens because __netdev_alloc_skb and __napi_alloc_skb can return a skb that is page backed or kmalloced depending on the requested size. As the result, the last small skb in the GRO packet can be kmalloced. There are three different locations where this can be fixed: (1) We could check head_frag in GRO and not allow GROing skbs with different head_frag. However, that would lead to performance regression on normal forward paths with unmodified gso_size, where !head_frag in the last packet is not a problem. (2) Set a flag in bpf_skb_net_grow and bpf_skb_net_shrink indicating that NETIF_F_SG is undesirable. That would need to eat a bit in sk_buff. Furthermore, that flag can be unset when all skbs on the frag_list are page backed. To retain good performance, bpf_skb_net_grow/shrink would have to walk the frag_list. (3) Walk the frag_list in skb_segment when determining whether NETIF_F_SG should be cleared. This of course slows things down. This patch implements (3). To limit the performance impact in skb_segment, the list is walked only for skbs with SKB_GSO_DODGY set that have gso_size changed. Normal paths thus will not hit it. We could check only the last skb but since we need to walk the whole list anyway, let's stay on the safe side.

Scores

EPSS (exploitation in 30 days)

0.53% · top 55% of all CVEs (7 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.

Affected products

• Linux · Linux

  • affected 162a5a8c3aff15c449e6b38355cdf80ab4f77a5a – < 5876b7f249a1ecbbcc8e35072c3828d6526d1c3a
  • affected 55fb612bef7fd237fb70068e2b6ff1cd1543a8ef – < 0a9f56e525ea871d3950b90076912f5c7494f00f
  • affected 821302dd0c51d29269ef73a595bdff294419e2cd – < bd5362e58721e4d0d1a37796593bd6e51536ce7a
  • affected 3dcbdb134f329842a38f0e6797191b885ab00a00 – < 65ad047fd83502447269fda8fd26c99077a9af47
  • affected 3dcbdb134f329842a38f0e6797191b885ab00a00 – < 50868de7dc4e7f0fcadd6029f32bf4387c102ee6
  • affected 3dcbdb134f329842a38f0e6797191b885ab00a00 – < ad25a115f50800c6847e0d841c5c7992a9f7c1b3
  • affected 3dcbdb134f329842a38f0e6797191b885ab00a00 – < 598d9e30927b15731e83797fbd700ecf399f42dd
  • affected 3dcbdb134f329842a38f0e6797191b885ab00a00 – < 9e4b7a99a03aefd37ba7bb1f022c8efab5019165
  • affected 92984818ff8cfd97311a5e0ac27f148a00df2b54
  • affected 4.9.194 – < 4.9.334
  • affected 4.14.145 – < 4.14.300
  • affected 4.19.74 – < 4.19.267
  • affected 5.2.16 – < 5.3

• Linux · Linux

  • affected 5.3
  • unaffected < 5.3
  • unaffected 4.9.334 – ≤ 4.9.*
  • unaffected 4.14.300 – ≤ 4.14.*
  • unaffected 4.19.267 – ≤ 4.19.*
  • unaffected 5.4.225 – ≤ 5.4.*
  • unaffected 5.10.155 – ≤ 5.10.*
  • unaffected 5.15.79 – ≤ 5.15.*
  • unaffected 6.0.9 – ≤ 6.0.*
  • unaffected 6.1 – ≤ *

References (8)

• https://git.kernel.org/stable/c/5876b7f249a1ecbbcc8e35072c3828d6526d1c3a (opens in a new tab)
• https://git.kernel.org/stable/c/0a9f56e525ea871d3950b90076912f5c7494f00f (opens in a new tab)
• https://git.kernel.org/stable/c/bd5362e58721e4d0d1a37796593bd6e51536ce7a (opens in a new tab)
• https://git.kernel.org/stable/c/65ad047fd83502447269fda8fd26c99077a9af47 (opens in a new tab)
• https://git.kernel.org/stable/c/50868de7dc4e7f0fcadd6029f32bf4387c102ee6 (opens in a new tab)
• https://git.kernel.org/stable/c/ad25a115f50800c6847e0d841c5c7992a9f7c1b3 (opens in a new tab)
• https://git.kernel.org/stable/c/598d9e30927b15731e83797fbd700ecf399f42dd (opens in a new tab)
• https://git.kernel.org/stable/c/9e4b7a99a03aefd37ba7bb1f022c8efab5019165 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

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Record last updated 5 Aug 2026, 08:56 UTC.