net: sched: act_csum: validate nested VLAN headers
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 4.20
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: net: sched: act_csum: validate nested VLAN headers tcf_csum_act() walks nested VLAN headers directly from skb->data when an skb still carries in-payload VLAN tags. The current code reads vlan->h_vlan_encapsulated_proto and then pulls VLAN_HLEN bytes without first ensuring that the full VLAN header is present in the linear area. If only part of an inner VLAN header is linearized, accessing h_vlan_encapsulated_proto reads past the linear area, and the following skb_pull(VLAN_HLEN) may violate skb invariants. Fix this by requiring pskb_may_pull(skb, VLAN_HLEN) before accessing and pulling each nested VLAN header. If the header still is not fully available, drop the packet through the existing error path.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From 4.19.99 · fixed in 4.20
- Linux Linux
5.1
References 8
git.kernel.org
- stable/c/0410c619e86551677fb79887a38eccad3f5a0725
- stable/c/886469b6455611a511aa6013e957e15e50577513
- stable/c/46c07ad50fa2f4ba7663ee1b72b75ad7ad45cf09
- stable/c/eb3765b90eb8f2a3d6310a80c14a9e57ec4267a2
- stable/c/a69738efea0996d05a3c7d2178551b891744df1b
- stable/c/ec4930979b3f7bbeb7af5744599fc6603a4dba62
- stable/c/3d165d975305cf76ff0b10a3c798fb31e5f5f9a5
- stable/c/c842743d073bdd683606cb414eb0ca84465dd834