{"cve":"CVE-2023-52894","nvd":{"published":"2024-08-21T07:15:05.943","modified":"2026-06-17T06:43:52.763","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_ncm: fix potential NULL ptr deref in ncm_bitrate()\n\nIn Google internal bug 265639009 we've received an (as yet) unreproducible\ncrash report from an aarch64 GKI 5.10.149-android13 running device.\n\nAFAICT the source code is at:\n  https://android.googlesource.com/kernel/common/+/refs/tags/ASB-2022-12-05_13-5.10\n\nThe call stack is:\n  ncm_close() -> ncm_notify() -> ncm_do_notify()\nwith the crash at:\n  ncm_do_notify+0x98/0x270\nCode: 79000d0b b9000a6c f940012a f9400269 (b9405d4b)\n\nWhich I believe disassembles to (I don't know ARM assembly, but it looks sane enough to me...):\n\n  // halfword (16-bit) store presumably to event->wLength (at offset 6 of struct usb_cdc_notification)\n  0B 0D 00 79    strh w11, [x8, #6]\n\n  // word (32-bit) store presumably to req->Length (at offset 8 of struct usb_request)\n  6C 0A 00 B9    str  w12, [x19, #8]\n\n  // x10 (NULL) was read here from offset 0 of valid pointer x9\n  // IMHO we're reading 'cdev->gadget' and getting NULL\n  // gadget is indeed at offset 0 of struct usb_composite_dev\n  2A 01 40 F9    ldr  x10, [x9]\n\n  // loading req->buf pointer, which is at offset 0 of struct usb_request\n  69 02 40 F9    ldr  x9, [x19]\n\n  // x10 is null, crash, appears to be attempt to read cdev->gadget->max_speed\n  4B 5D 40 B9    ldr  w11, [x10, #0x5c]\n\nwhich seems to line up with ncm_do_notify() case NCM_NOTIFY_SPEED code fragment:\n\n  event->wLength = cpu_to_le16(8);\n  req->length = NCM_STATUS_BYTECOUNT;\n\n  /* SPEED_CHANGE data is up/down speeds in bits/sec */\n  data = req->buf + sizeof *event;\n  data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));\n\nMy analysis of registers and NULL ptr deref crash offset\n  (Unable to handle kernel NULL pointer dereference at virtual address 000000000000005c)\nheavily suggests that the crash is due to 'cdev->gadget' being NULL when executing:\n  data[0] = cpu_to_le32(ncm_bitrate(cdev->gadget));\nwhich calls:\n  ncm_bitrate(NULL)\nwhich then calls:\n  gadget_is_superspeed(NULL)\nwhich reads\n  ((struct usb_gadget *)NULL)->max_speed\nand hits a panic.\n\nAFAICT, if I'm counting right, the offset of max_speed is indeed 0x5C.\n(remember there's a GKI KABI reservation of 16 bytes in struct work_struct)\n\nIt's not at all clear to me how this is all supposed to work...\nbut returning 0 seems much better than panic-ing...","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/09e4507ec8ef2d44da6ba4092b8ee2d81f216497","https://git.kernel.org/stable/c/63d161f29cd39c050e8873aa36e0c9fc013bb763","https://git.kernel.org/stable/c/a21da7f7aae618c785f7e4a275d43c06dc8412b6","https://git.kernel.org/stable/c/a69c8dfb85b44be9cc223be07d35cc3a9baefbea","https://git.kernel.org/stable/c/c6ec929595c7443250b2a4faea988c62019d5cd2"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:54:16.205165117+00:00"},"epss":{"cve":"CVE-2023-52894","score":0.00243,"percentile":0.15498,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}