{"id":"CVE-2026-52997","state":"PUBLISHED","title":"net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()","description":"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.","publishedAt":"2026-06-24T16:29:09.997Z","updatedAt":"2026-06-24T16:29:09.997Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"320d031ad6e4d67e8e1ab08ac71efda02bc85683","status":"affected","lessThan":"86cf2eba2056bcf9c41fba260e599bd95bf9943b","versionType":"git"},{"version":"320d031ad6e4d67e8e1ab08ac71efda02bc85683","status":"affected","lessThan":"3042add80c2c50bd127d570b83319af612efde65","versionType":"git"},{"version":"320d031ad6e4d67e8e1ab08ac71efda02bc85683","status":"affected","lessThan":"478ed6b7d2577439c610f91fa8759a4c878a4264","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_dualpi2.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_dualpi2.c"]}],"references":["https://git.kernel.org/stable/c/86cf2eba2056bcf9c41fba260e599bd95bf9943b","https://git.kernel.org/stable/c/3042add80c2c50bd127d570b83319af612efde65","https://git.kernel.org/stable/c/478ed6b7d2577439c610f91fa8759a4c878a4264"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:16.098Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/52xxx/CVE-2026-52997.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-52997","state":"PUBLISHED","datePublished":"2026-06-24T16:29:09.997Z","dateUpdated":"2026-06-24T16:29:09.997Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-06-09T07:44:35.377Z"},"containers":{"cna":{"title":"net/sched: sch_dualpi2: drain both C-queue and L-queue in dualpi2_change()","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"320d031ad6e4d67e8e1ab08ac71efda02bc85683","status":"affected","lessThan":"86cf2eba2056bcf9c41fba260e599bd95bf9943b","versionType":"git"},{"version":"320d031ad6e4d67e8e1ab08ac71efda02bc85683","status":"affected","lessThan":"3042add80c2c50bd127d570b83319af612efde65","versionType":"git"},{"version":"320d031ad6e4d67e8e1ab08ac71efda02bc85683","status":"affected","lessThan":"478ed6b7d2577439c610f91fa8759a4c878a4264","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_dualpi2.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.17","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.17","versionType":"semver"},{"version":"6.18.33","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.0.10","status":"unaffected","lessThanOrEqual":"7.0.*","versionType":"semver"},{"version":"7.1","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/sch_dualpi2.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/86cf2eba2056bcf9c41fba260e599bd95bf9943b"},{"url":"https://git.kernel.org/stable/c/3042add80c2c50bd127d570b83319af612efde65"},{"url":"https://git.kernel.org/stable/c/478ed6b7d2577439c610f91fa8759a4c878a4264"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-06-24T16:29:09.997Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"6.18.33"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.0.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.17","versionEndExcluding":"7.1"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}