{"id":"DEBIAN-CVE-2023-52894","details":"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() -\u003e ncm_notify() -\u003e 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-\u003ewLength (at offset 6 of struct usb_cdc_notification)   0B 0D 00 79    strh w11, [x8, #6]    // word (32-bit) store presumably to req-\u003eLength (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-\u003egadget' and getting NULL   // gadget is indeed at offset 0 of struct usb_composite_dev   2A 01 40 F9    ldr  x10, [x9]    // loading req-\u003ebuf 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-\u003egadget-\u003emax_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-\u003ewLength = cpu_to_le16(8);   req-\u003elength = NCM_STATUS_BYTECOUNT;    /* SPEED_CHANGE data is up/down speeds in bits/sec */   data = req-\u003ebuf + sizeof *event;   data[0] = cpu_to_le32(ncm_bitrate(cdev-\u003egadget));  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-\u003egadget' being NULL when executing:   data[0] = cpu_to_le32(ncm_bitrate(cdev-\u003egadget)); which calls:   ncm_bitrate(NULL) which then calls:   gadget_is_superspeed(NULL) which reads   ((struct usb_gadget *)NULL)-\u003emax_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...","modified":"2026-09-15T09:03:02.352249085Z","published":"2024-08-21T07:15:05.943Z","upstream":["CVE-2023-52894"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2023-52894"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:12","purl":"pkg:deb/debian/linux?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52894.json"}},{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52894.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2023-52894.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}