{"id":"CVE-2026-90055","summary":"usb: atm: usbatm: fix invalid ci_range initialization","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: atm: usbatm: fix invalid ci_range initialization\n\nsyzbot reported a shift-out-of-bounds in __vcc_connect():\n\n  UBSAN: shift-out-of-bounds in net/atm/common.c:382:32\n  shift exponent -1 is negative\n  CPU: 0 UID: 0 PID: 5987 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full)\n  Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026\n  Call Trace:\n   \u003cTASK\u003e\n   dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120\n   ubsan_epilogue+0xa/0x30 lib/ubsan.c:233\n   __ubsan_handle_shift_out_of_bounds+0x36d/0x400 lib/ubsan.c:494\n   __vcc_connect+0x14b4/0x19c0 net/atm/common.c:382\n   vcc_connect+0x328/0x8f0 net/atm/common.c:498\n   pvc_bind+0x272/0x380 net/atm/pvc.c:52\n   __sys_bind+0x2e3/0x410 net/socket.c:1976\n   __x64_sys_bind+0x7a/0x90 net/socket.c:1979\n   ...\n\nATM device ci_range fields (vpi_bits and vci_bits) represent the\nnumber of bits supported for VPI and VCI addressing on the device.\nnet/atm/common.c directly uses these fields as bit shift counts:\n  vpi \u003e\u003e dev-\u003eci_range.vpi_bits\n  vci \u003e\u003e dev-\u003eci_range.vci_bits\n  1 \u003c\u003c vcc-\u003edev-\u003eci_range.vpi_bits\n  1 \u003c\u003c vcc-\u003edev-\u003eci_range.vci_bits\n\nusbatm_atm_init() sets ci_range.vpi_bits and ci_range.vci_bits to\nATM_CI_MAX (-1), which is defined in \u003cuapi/linux/atmdev.h\u003e as a\nsentinel value for userspace ATM_SETCIRANGE requests, not a valid bit\ncount. Shifting by -1 is undefined behavior and triggers UBSAN\nwarnings.\n\nATM UNI cell headers allow up to 8 bits for VPI (0..255) and 16 bits\nfor VCI (0..65535). Initialize vpi_bits to 8 and vci_bits to 16, as\ndone by solos-pci.","modified":"2026-09-19T03:47:24.382355976Z","published":"2026-09-17T16:05:40.304Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90055.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/1e964d414bfd9f8dfe9948d08e4b9dda4ed2e422"},{"type":"WEB","url":"https://git.kernel.org/stable/c/561cbd6d49022c9a383e22a39c87a165a4d39f9c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/75667703115154a4fd9cf259d4f826d8729cbcda"},{"type":"WEB","url":"https://git.kernel.org/stable/c/76bc7c3a44856744b64aa91d9afe6d9522a78c42"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7baa0c92be39eb3da755ed6f200497a57078c47b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8442586526c406527bf31206e538c0ce6bc672e6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a60fd8c6dbaa76da4163cf225ed2b9e982540f39"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ff7f77a234f7b74e5955a6e34fa74eca4c9ca44c"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90055.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90055"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"c59bba75fa500f13ef14215d599ee0d7faa1b954"},{"fixed":"8442586526c406527bf31206e538c0ce6bc672e6"},{"fixed":"561cbd6d49022c9a383e22a39c87a165a4d39f9c"},{"fixed":"76bc7c3a44856744b64aa91d9afe6d9522a78c42"},{"fixed":"7baa0c92be39eb3da755ed6f200497a57078c47b"},{"fixed":"1e964d414bfd9f8dfe9948d08e4b9dda4ed2e422"},{"fixed":"ff7f77a234f7b74e5955a6e34fa74eca4c9ca44c"},{"fixed":"75667703115154a4fd9cf259d4f826d8729cbcda"},{"fixed":"a60fd8c6dbaa76da4163cf225ed2b9e982540f39"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90055.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.13"},{"fixed":"5.10.270"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.11.0"},{"fixed":"5.15.221"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.188"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90055.json"}}],"schema_version":"1.9.0"}