net/sched: act_gact, act_police: range check the fallback control action

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74620
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-22 16:16:34 UTC
Updated2026-08-23 13:16:47 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net/sched: act_gact, act_police: range check the fallback control action tcf_action_check_ctrlact() range checks the primary control action: if (!opcode) ret = action > TC_ACT_VALUE_MAX ? -EINVAL : 0; TC_ACT_VALUE_MAX is TC_ACT_TRAP, so kernel-internal verdicts above it cannot be set that way. But act_gact and act_police each carry a second, independent control action supplied by user space that never reaches that helper - TCA_GACT_PROB.paction and TCA_POLICE_RESULT. Both only reject TC_ACT_GOTO_CHAIN, so any other value is stored verbatim and returned verbatim from the action. In particular user space can store TC_ACT_CONSUMED, which is TC_ACT_VALUE_MAX + 1 and is deliberately not part of the UAPI value range. That verdict tells every caller the action took ownership of the skb, so nobody frees it: sch_handle_ingress(), sch_handle_egress() and tcf_qevent_handle() all deliberately skip the free for it. The result is one leaked sk_buff plus its data buffer per packet traversing the filter, unbounded, for all traffic on the chain including kernel-generated packets. Both are trivially deterministic. act_gact clamps tcfg_pval to >= 1, so with pval = 1 gact_determ() returns the fallback for every packet. act_police has no mandatory rate, so rate = 0 leaves tcfp_mtu = ~0 and tcf_police_mtu_check() always passes. TC_ACT_CONSUMED was added by commit 720f22fed81b ("net: sched: refactor reinsert action"), after both goto-chain guards were written: commit 9469f375ab09 ("net/sched: act_gact: disallow 'goto chain' on fallback control action") and commit c08f5ed5d625 ("net/sched: act_police: disallow 'goto chain' on fallback control action"). Neither guard was widened when the new verdict appeared. Factor the existing range test out of tcf_action_check_ctrlact() as tcf_action_valid() and apply it to both fallbacks. The helper cannot call tcf_action_check_ctrlact() directly because that also allocates a goto_chain, which is exactly what these two sites must not do. Reproduced on v7.2-rc6: kmemleak reports one leaked 232-byte skbuff_head_cache object plus its 704-byte data buffer per packet. With this patch both configurations are rejected with -EINVAL and kmemleak reports none.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 5f038affdacaffedf6a85a06cf59ec0a852d36a7 git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4 git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 725efc2ab4a40affc4e285a2dc4896d103948a6c git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 6bcb8839aa2d686964a4154650afc4db91e1c514 git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 5344e01179baa37547ab29fd7b8614f83faa190c git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 92f00f1d4d204a428b38e26fce3baee144b6955d git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 2e8df8c9190335475a3b64a159d3efd8cdd1cb73 git Not specified
CNA Linux Linux affected 720f22fed81bc6fd1765db7014651b6718887bea 883b56ae58fe657d8497806c7059646e9ba6dbd0 git Not specified
CNA Linux Linux affected 5.3 Not specified
CNA Linux Linux unaffected 5.3 semver Not specified
CNA Linux Linux unaffected 5.10.266 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.152 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.104 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.45 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.9 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/efa58aeb6a99028b1fbc3ab2f31ba3a881211ad4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6bcb8839aa2d686964a4154650afc4db91e1c514 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/92f00f1d4d204a428b38e26fce3baee144b6955d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/725efc2ab4a40affc4e285a2dc4896d103948a6c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2e8df8c9190335475a3b64a159d3efd8cdd1cb73 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/883b56ae58fe657d8497806c7059646e9ba6dbd0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5f038affdacaffedf6a85a06cf59ec0a852d36a7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5344e01179baa37547ab29fd7b8614f83faa190c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

© CVE.report 2026

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

Free CVE JSON API cve.report/api

CVE.report and Source URL Uptime Status status.cve.report