CyberRota Analysis
AI-GeneratedThe vulnerability in the Linux kernel affects the dualpi2 queuing discipline, where a race condition can lead to a null pointer dereference during packet processing. This flaw occurs when the queue length (qlen) is incorrectly managed, potentially causing system crashes or instability. Organizations utilizing Linux systems with this kernel version should prioritize patching to mitigate risks associated with this issue.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: net/sched: sch_dualpi2: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen Whenever dualpi2 drops packets during peek, it calls qdisc_tree_reduce_backlog. An issue arises because it calls qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops to zero, but peek returns an skb, the parent's qlen_notify callback will be executed even though dualpi2 still has 1 packet on the queue and, thus, mistakenly deactivates the parent's class which leads to a null-ptr-deref: [ 101.427314][ T599] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI [ 101.427755][ T599] KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f] [ 101.428048][ T599] CPU: 2 UID: 0 PID: 599 Comm: ping Not tainted 7.1.0-rc5-00284-gbce53c430ed7 #102 PREEMPT(full) [ 101.428400][ T599] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 101.428608][ T599] RIP: 0010:qfq_dequeue (net/sched/sch_qfq.c:1150) sch_qfq [ 101.428821][ T599] Code: 00 fc ff df 80 3c 02 00 0f 85 46 0c 00 00 4c 8d 73 48 48 89 9d b8 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <80> 3c 02 00 0f 85 2d 0c 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b All code [ 101.429348][ T599] RSP: 0018:ffff8881110df4f0 EFLAGS: 00010216 [ 101.429541][ T599] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: dffffc0000000000 [ 101.429763][ T599] RDX: 0000000000000009 RSI: 00000024c0000000 RDI: ffff88811436c2b0 [ 101.429985][ T599] RBP: ffff88811436c000 R08: ffff88811436c280 R09: 1ffff11021277523 [ 101.430206][ T599] R10: 1ffff11021277526 R11: 1ffff11021277527 R12: 00000024c0000000 [ 101.430423][ T599] R13: ffff88811436c2b8 R14: 0000000000000048 R15: 0000000020000000 [ 101.430642][ T599] FS: 00007f61813e1c40(0000) GS:ffff8881691ef000(0000) knlGS:0000000000000000 [ 101.430913][ T599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 101.431100][ T599] CR2: 00005651650850a8 CR3: 000000010ca0b000 CR4: 0000000000750ef0 [ 101.431320][ T599] PKRU: 55555554 [ 101.431433][ T599] Call Trace: [ 101.431544][ T599] <TASK> [ 101.431628][ T599] __qdisc_run (net/sched/sch_generic.c:322 net/sched/sch_generic.c:427 net/sched/sch_generic.c:445) [ 101.431792][ T599] ? dev_qdisc_enqueue (./include/trace/events/qdisc.h:49 (discriminator 22) net/core/dev.c:4176 (discriminator 22)) [ 101.431941][ T599] __dev_queue_xmit (./include/net/pkt_sched.h:120 ./include/net/pkt_sched.h:117 net/core/dev.c:4292 net/core/dev.c:4831) Fix this by only calling qdisc_tree_reduce_backlog in peek after the qlen is restored.