medium 5.5

CVE-2023-52894 json

usb: gadget: f_ncm: fix potential NULL ptr deref in ncm_bitrate()

published 2024-08-21 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-59605

cvss: 5.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits: 0; none known

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

In Google internal bug 265639009 we've received an (as yet) unreproducible crash report from an aarch64 GKI 5.10.149-android13 running device.

AFAICT the source code is at: https://android.googlesource.com/kernel/common/+/refs/tags/ASB-2022-12-05_13-5.10

The call stack is: ncm_close() -> ncm_notify() -> ncm_do_notify() with the crash at: ncm_do_notify+0x98/0x270 Code: 79000d0b b9000a6c f940012a f9400269 (b9405d4b)

Which I believe disassembles to (I don't know ARM assembly, but it looks sane enough to me...):

// halfword (16-bit) store presumably to event->wLength (at offset 6 of struct usb_cdc_notification) 0B 0D 00 79 strh w11, [x8, #6]

// word (32-bit) store presumably to req->Length (at offset 8 of struct usb_request) 6C 0A 00 B9 str w12, [x19, #8]

// x10 (NULL) was read here from offset 0 of valid pointer x9 // IMHO we're reading 'cdev->gadget' and getting NULL // gadget is indeed at offset 0 of struct usb_composite_dev 2A 01 40 F9 ldr x10, [x9]

// loading req->buf pointer, which is at offset 0 of struct usb_request 69 02 40 F9 ldr x9, [x19]

// x10 is null, crash, appears to be attempt to read cdev->gadget->max_speed 4B 5D 40 B9 ldr w11, [x10, #0x5c]

which seems to line up with ncm_do_notify() case NCM_NOTIFY_SPEED code fragment:

event->wLength = cpu_to_le16(8); req->length = NCM_STATUS_BYTECOUNT;

/* SPEED_CHANGE data is up/down speeds in bits/sec */ data = req->buf + sizeof *event; data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));

My analysis of registers and NULL ptr deref crash offset (Unable to handle kernel NULL pointer dereference at virtual address 000000000000005c) heavily suggests that the crash is due to 'cdev->gadget' being NULL when executing: data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget)); which calls: ncm_bitrate(NULL) which then calls: gadget_is_superspeed(NULL) which reads ((struct usb_gadget *)NULL)->max_speed and hits a panic.

AFAICT, if I'm counting right, the offset of max_speed is indeed 0x5C. (remember there's a GKI KABI reservation of 16 bytes in struct work_struct)

It's not at all clear to me how this is all supposed to work... but returning 0 seems much better than panic-ing...

Patch / fix

fixed in 1 distros 3 links 7

Linux Linux 4.14.304, 4.19.271, 5.4.230, 5.10.165, 5.15.90, 6.1.8, 6.2

debian ubuntu suse

linux Debian 14, Debian 13, Debian 12 6.1.8-1

debian advisories DEBIAN-CVE-2023-52894

linux Ubuntu 18.04 LTS 4.15.0-209.220
linux Ubuntu 20.04 LTS 5.4.0-147.164
linux Ubuntu 22.04 LTS 5.15.0-70.77
linux-aws Ubuntu 18.04 LTS 4.15.0-1154.167
linux-aws Ubuntu 20.04 LTS 5.4.0-1100.108
linux-aws Ubuntu 22.04 LTS 5.15.0-1034.38
linux-gcp Ubuntu 20.04 LTS 5.4.0-1103.112
linux-gcp Ubuntu 22.04 LTS 5.15.0-1032.40

ubuntu advisories UBUNTU-CVE-2023-52894

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

dtb-aarch64 openSUSE Leap 15.5 5.14.21-150500.55.80.1
kernel-64kb SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.80.2
kernel-syms SLE Module for Development Tools 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.80.1
kernel-obs-qa openSUSE Leap 15.5 5.14.21-150500.55.80.1
kernel-source SLE Module for Development Tools 15 SP5, SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.80.2
kernel-default SLE Workstation Extension 15 SP5, SLE Module for Legacy 15 SP5, SLE Module for Basesystem 15 SP5 +5 more 5.14.21-150500.55.80.2
kernel-kvmsmall openSUSE Leap 15.5 5.14.21-150500.55.80.2
kernel-zfcpdump SLE Module for Basesystem 15 SP5, openSUSE Leap 15.5 5.14.21-150500.55.80.2

suse advisories SUSE-SU-2024:3483-1 SUSE-SU-2024:3408-1 SUSE-SU-2024:3227-1 SUSE-SU-2024:3209-1 SUSE-SU-2024:3190-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-52894 updated 2026-11-05 cvss 5.5

kernel: usb: gadget: f_ncm: fix potential NULL ptr deref in ncm_bitrate()

Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-09-10)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	5.5	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-476 NULL Pointer Dereference

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2023-52894
NVD CVE-2023-52894

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary