{ "threat_severity" : "Moderate", "public_date" : "2024-05-19T00:00:00Z", "bugzilla" : { "description" : "kernel: net/sched: fix lockdep splat in qdisc_tree_reduce_backlog()", "id" : "2281684", "url" : "https://bugzilla.redhat.com/show_bug.cgi?id=2281684" }, "cvss3" : { "cvss3_base_score" : "5.5", "cvss3_scoring_vector" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status" : "verified" }, "details" : [ "In the Linux kernel, the following vulnerability has been resolved:\nnet/sched: fix lockdep splat in qdisc_tree_reduce_backlog()\nqdisc_tree_reduce_backlog() is called with the qdisc lock held,\nnot RTNL.\nWe must use qdisc_lookup_rcu() instead of qdisc_lookup()\nsyzbot reported:\nWARNING: suspicious RCU usage\n6.1.74-syzkaller #0 Not tainted\n-----------------------------\nnet/sched/sch_api.c:305 suspicious rcu_dereference_protected() usage!\nother info that might help us debug this:\nrcu_scheduler_active = 2, debug_locks = 1\n3 locks held by udevd/1142:\n#0: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:306 [inline]\n#0: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]\n#0: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: net_tx_action+0x64a/0x970 net/core/dev.c:5282\n#1: ffff888171861108 (&sch->q.lock){+.-.}-{2:2}, at: spin_lock include/linux/spinlock.h:350 [inline]\n#1: ffff888171861108 (&sch->q.lock){+.-.}-{2:2}, at: net_tx_action+0x754/0x970 net/core/dev.c:5297\n#2: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:306 [inline]\n#2: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:747 [inline]\n#2: ffffffff87c729a0 (rcu_read_lock){....}-{1:2}, at: qdisc_tree_reduce_backlog+0x84/0x580 net/sched/sch_api.c:792\nstack backtrace:\nCPU: 1 PID: 1142 Comm: udevd Not tainted 6.1.74-syzkaller #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024\nCall Trace:\n\n[] __dump_stack lib/dump_stack.c:88 [inline]\n[] dump_stack_lvl+0x1b1/0x28f lib/dump_stack.c:106\n[] dump_stack+0x15/0x1e lib/dump_stack.c:113\n[] lockdep_rcu_suspicious+0x1b9/0x260 kernel/locking/lockdep.c:6592\n[] qdisc_lookup+0xac/0x6f0 net/sched/sch_api.c:305\n[] qdisc_tree_reduce_backlog+0x243/0x580 net/sched/sch_api.c:811\n[] pfifo_tail_enqueue+0x32c/0x4b0 net/sched/sch_fifo.c:51\n[] qdisc_enqueue include/net/sch_generic.h:833 [inline]\n[] netem_dequeue+0xeb3/0x15d0 net/sched/sch_netem.c:723\n[] dequeue_skb net/sched/sch_generic.c:292 [inline]\n[] qdisc_restart net/sched/sch_generic.c:397 [inline]\n[] __qdisc_run+0x249/0x1e60 net/sched/sch_generic.c:415\n[] qdisc_run+0xd6/0x260 include/net/pkt_sched.h:125\n[] net_tx_action+0x7c9/0x970 net/core/dev.c:5313\n[] __do_softirq+0x2bd/0x9bd kernel/softirq.c:616\n[] invoke_softirq kernel/softirq.c:447 [inline]\n[] __irq_exit_rcu+0xca/0x230 kernel/softirq.c:700\n[] irq_exit_rcu+0x9/0x20 kernel/softirq.c:712\n[] sysvec_apic_timer_interrupt+0x42/0x90 arch/x86/kernel/apic/apic.c:1107\n[] asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:656", "CVE-2024-35892 is a vulnerability in the Linux kernel’s network scheduler caused by improper use of the qdisc_lookup() function. This function assumes the global RTNL lock is held, but in the qdisc_tree_reduce_backlog() function, only a local queue lock is used. This mismatch creates a race condition that could lead to system instability or crashes. The issue has been fixed by replacing qdisc_lookup() with an RCU-safe version that works correctly in this context." ], "affected_release" : [ { "product_name" : "Red Hat Enterprise Linux 9", "release_date" : "2024-11-12T00:00:00Z", "advisory" : "RHSA-2024:9315", "cpe" : "cpe:/a:redhat:enterprise_linux:9", "package" : "kernel-0:5.14.0-503.11.1.el9_5" }, { "product_name" : "Red Hat Enterprise Linux 9", "release_date" : "2024-11-12T00:00:00Z", "advisory" : "RHSA-2024:9315", "cpe" : "cpe:/o:redhat:enterprise_linux:9", "package" : "kernel-0:5.14.0-503.11.1.el9_5" } ], "package_state" : [ { "product_name" : "Red Hat Enterprise Linux 6", "fix_state" : "Out of support scope", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:6" }, { "product_name" : "Red Hat Enterprise Linux 7", "fix_state" : "Out of support scope", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:7" }, { "product_name" : "Red Hat Enterprise Linux 7", "fix_state" : "Out of support scope", "package_name" : "kernel-rt", "cpe" : "cpe:/o:redhat:enterprise_linux:7" }, { "product_name" : "Red Hat Enterprise Linux 8", "fix_state" : "Not affected", "package_name" : "kernel", "cpe" : "cpe:/o:redhat:enterprise_linux:8" }, { "product_name" : "Red Hat Enterprise Linux 8", "fix_state" : "Not affected", "package_name" : "kernel-rt", "cpe" : "cpe:/o:redhat:enterprise_linux:8" }, { "product_name" : "Red Hat Enterprise Linux 9", "fix_state" : "Affected", "package_name" : "kernel-rt", "cpe" : "cpe:/o:redhat:enterprise_linux:9" } ], "references" : [ "https://www.cve.org/CVERecord?id=CVE-2024-35892\nhttps://nvd.nist.gov/vuln/detail/CVE-2024-35892\nhttps://lore.kernel.org/linux-cve-announce/2024051949-CVE-2024-35892-0f0c@gregkh/T" ], "name" : "CVE-2024-35892", "csaw" : false }