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

Description

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: f_ncm: fix potential NULL ptr deref in ncm_bitrate() 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...

Timeline

Scores

EPSS (exploitation in 30 days)

0.24% · top 84% of all CVEs (7 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.

Weakness

• CWE-476 (opens in a new tab)All about CWE-476 and its CVEs

Affected products

• Linux · Linux

  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < fef6b29671b66dfb71f17e337c1ad14b5a2cedae
  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < 63d161f29cd39c050e8873aa36e0c9fc013bb763
  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < a21da7f7aae618c785f7e4a275d43c06dc8412b6
  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < e92c70059178da751e5af7de02384b7dfadb5ec7
  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < a69c8dfb85b44be9cc223be07d35cc3a9baefbea
  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < 09e4507ec8ef2d44da6ba4092b8ee2d81f216497
  • affected 1650113888fe7b7e16604a5019c32dd3ddeb3af2 – < c6ec929595c7443250b2a4faea988c62019d5cd2

• Linux · Linux

  • affected 4.9
  • unaffected < 4.9
  • unaffected 4.14.304 – ≤ 4.14.*
  • unaffected 4.19.271 – ≤ 4.19.*
  • unaffected 5.4.230 – ≤ 5.4.*
  • unaffected 5.10.165 – ≤ 5.10.*
  • unaffected 5.15.90 – ≤ 5.15.*
  • unaffected 6.1.8 – ≤ 6.1.*
  • unaffected 6.2 – ≤ *

References (7)

• https://git.kernel.org/stable/c/fef6b29671b66dfb71f17e337c1ad14b5a2cedae (opens in a new tab)
• https://git.kernel.org/stable/c/63d161f29cd39c050e8873aa36e0c9fc013bb763 (opens in a new tab)
• https://git.kernel.org/stable/c/a21da7f7aae618c785f7e4a275d43c06dc8412b6 (opens in a new tab)
• https://git.kernel.org/stable/c/e92c70059178da751e5af7de02384b7dfadb5ec7 (opens in a new tab)
• https://git.kernel.org/stable/c/a69c8dfb85b44be9cc223be07d35cc3a9baefbea (opens in a new tab)
• https://git.kernel.org/stable/c/09e4507ec8ef2d44da6ba4092b8ee2d81f216497 (opens in a new tab)
• https://git.kernel.org/stable/c/c6ec929595c7443250b2a4faea988c62019d5cd2 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2023-52894](https://trackcve.app/badge/CVE-2023-52894.svg)](https://trackcve.app/cve/CVE-2023-52894)

Record last updated 11 May 2026, 19:35 UTC.