CVE-2021-47268 usb: typec: tcpm: cancel vdm and state machine hrtimer when unregister tcpm port

What is CVE-2021-47268?

CVE-2021-47268 is a high-severity use after free vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

usb: typec: tcpm: cancel vdm and state machine hrtimer when unregister tcpm port

A pending hrtimer may expire after the kthread_worker of tcpm port is destroyed, see below kernel dump when do module unload, fix it by cancel the 2 hrtimers.

[ 111.517018] Unable to handle kernel paging request at virtual address ffff8000118cb880 [ 111.518786] blk_update_request: I/O error, dev sda, sector 60061185 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 [ 111.526594] Mem abort info: [ 111.526597] ESR = 0x96000047 [ 111.526600] EC = 0x25: DABT (current EL), IL = 32 bits [ 111.526604] SET = 0, FnV = 0 [ 111.526607] EA = 0, S1PTW = 0 [ 111.526610] Data abort info: [ 111.526612] ISV = 0, ISS = 0x00000047 [ 111.526615] CM = 0, WnR = 1 [ 111.526619] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000041d75000 [ 111.526623] [ffff8000118cb880] pgd=10000001bffff003, p4d=10000001bffff003, pud=10000001bfffe003, pmd=10000001bfffa003, pte=0000000000000000 [ 111.526642] Internal error: Oops: 96000047 [#1] PREEMPT SMP [ 111.526647] Modules linked in: dwc3_imx8mp dwc3 phy_fsl_imx8mq_usb [last unloaded: tcpci] [ 111.526663] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.13.0-rc4-00927-gebbe9dbd802c-dirty #36 [ 111.526670] Hardware name: NXP i.MX8MPlus EVK board (DT) [ 111.526674] pstate: 800000c5 (Nzcv daIF -PAN -UAO -TCO BTYPE=--) [ 111.526681] pc : queued_spin_lock_slowpath+0x1a0/0x390 [ 111.526695] lr : _raw_spin_lock_irqsave+0x88/0xb4 [ 111.526703] sp : ffff800010003e20 [ 111.526706] x29: ffff800010003e20 x28: ffff00017f380180 [ 111.537156] buffer_io_error: 6 callbacks suppressed [ 111.537162] Buffer I/O error on dev sda1, logical block 60040704, async page read [ 111.539932] x27: ffff00017f3801c0 [ 111.539938] x26: ffff800010ba2490 x25: 0000000000000000 x24: 0000000000000001 [ 111.543025] blk_update_request: I/O error, dev sda, sector 60061186 op 0x0:(READ) flags 0x0 phys_seg 7 prio class 0 [ 111.548304] [ 111.548306] x23: 00000000000000c0 x22: ffff0000c2a9f184 x21: ffff00017f380180 [ 111.551374] Buffer I/O error on dev sda1, logical block 60040705, async page read [ 111.554499] [ 111.554503] x20: ffff0000c5f14210 x19: 00000000000000c0 x18: 0000000000000000 [ 111.557391] Buffer I/O error on dev sda1, logical block 60040706, async page read [ 111.561218] [ 111.561222] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 [ 111.564205] Buffer I/O error on dev sda1, logical block 60040707, async page read [ 111.570887] x14: 00000000000000f5 x13: 0000000000000001 x12: 0000000000000040 [ 111.570902] x11: ffff0000c05ac6d8 [ 111.583420] Buffer I/O error on dev sda1, logical block 60040708, async page read [ 111.588978] x10: 0000000000000000 x9 : 0000000000040000 [ 111.588988] x8 : 0000000000000000 [ 111.597173] Buffer I/O error on dev sda1, logical block 60040709, async page read [ 111.605766] x7 : ffff00017f384880 x6 : ffff8000118cb880 [ 111.605777] x5 : ffff00017f384880 [ 111.611094] Buffer I/O error on dev sda1, logical block 60040710, async page read [ 111.617086] x4 : 0000000000000000 x3 : ffff0000c2a9f184 [ 111.617096] x2 : ffff8000118cb880 [ 111.622242] Buffer I/O error on dev sda1, logical block 60040711, async page read [ 111.626927] x1 : ffff8000118cb880 x0 : ffff00017f384888 [ 111.626938] Call trace: [ 111.626942] queued_spin_lock_slowpath+0x1a0/0x390 [ 111.795809] kthread_queue_work+0x30/0xc0 [ 111.799828] state_machine_timer_handler+0x20/0x30 [ 111.804624] __hrtimer_run_queues+0x140/0x1e0 [ 111.808990] hrtimer_interrupt+0xec/0x2c0 [ 111.813004] arch_timer_handler_phys+0x38/0x50 [ 111.817456] handle_percpu_devid_irq+0x88/0x150 [ 111.821991] __handle_domain_irq+0x80/0xe0 [ 111.826093] gic_handle_irq+0xc0/0x140 [ 111.829848] el1_irq+0xbc/0x154 [ 111.832991] arch_cpu_idle+0x1c/0x2c [ 111.836572] default_idle_call+0x24/0x6c [ 111.840497] do_idle+0x238/0x2ac [ 1 ---truncated---

Which versions are affected by CVE-2021-47268?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-47268?

Apply the vendor's patch.

Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.

Is CVE-2021-47268 being exploited?

There is no known exploitation of CVE-2021-47268 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2021-47268, GHSA-8g98-8rxj-3j4q, UBUNTU-CVE-2021-47268.