{"id":"CVE-2026-52997","summary":"net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()\n\nFix dualpi2_change() to correctly enforce updated limit and memlimit\nvalues after a configuration change of the dualpi2 qdisc.\n\nBefore this patch, dualpi2_change() always attempted to dequeue packets\nvia the root qdisc (C-queue) when reducing backlog or memory usage, and\nunconditionally assumed that a valid skb will be returned. When traffic\nclassification results in packets being queued in the L-queue while the\nC-queue is empty, this leads to a NULL skb dereference during limit or\nmemlimit enforcement.\n\nThis is fixed by first dequeuing from the C-queue path if it is\nnon-empty. Once the C-queue is empty, packets are dequeued directly from\nthe L-queue. Return values from qdisc_dequeue_internal() are checked for\nboth queues. When dequeuing from the L-queue, the parent qdisc qlen and\nbacklog counters are updated explicitly to keep overall qdisc statistics\nconsistent.","modified":"2026-07-08T08:05:24.659499453Z","published":"2026-06-24T16:29:09.997Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52997.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/3042add80c2c50bd127d570b83319af612efde65"},{"type":"WEB","url":"https://git.kernel.org/stable/c/478ed6b7d2577439c610f91fa8759a4c878a4264"},{"type":"WEB","url":"https://git.kernel.org/stable/c/86cf2eba2056bcf9c41fba260e599bd95bf9943b"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/52xxx/CVE-2026-52997.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-52997"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"320d031ad6e4d67e8e1ab08ac71efda02bc85683"},{"fixed":"86cf2eba2056bcf9c41fba260e599bd95bf9943b"},{"fixed":"3042add80c2c50bd127d570b83319af612efde65"},{"fixed":"478ed6b7d2577439c610f91fa8759a4c878a4264"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52997.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.17.0"},{"fixed":"6.18.33"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.0.10"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-52997.json"}}],"schema_version":"1.7.5"}