{"id":"CVE-2026-80973","summary":"ALSA: 6fire: bound the MIDI event length from the device","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: 6fire: bound the MIDI event length from the device\n\nusb6fire_comm_receiver_handler() forwards a MIDI event using a length\nbyte the device supplies, with no bound and no check that the transfer\ndelivered that many bytes:\n\n\tif (!urb-\u003estatus) {\n\t\tif (rt-\u003ereceiver_buffer[0] == 0x10) /* midi in event */\n\t\t\tif (midi_rt)\n\t\t\t\tmidi_rt-\u003ein_received(midi_rt,\n\t\t\t\t\t\trt-\u003ereceiver_buffer + 2,\n\t\t\t\t\t\trt-\u003ereceiver_buffer[1]);\n\t}\n\nreceiver_buffer is a 64-byte kzalloc() buffer (COMM_RECEIVER_BUFSIZE), so\nonly 62 bytes follow the two-byte header.  receiver_buffer[1] is a u8 the\ndevice chooses, so a device that answers with 0x10 and a length of 0xFF\nmakes snd_rawmidi_receive() read 255 bytes starting two bytes into a\n64-byte object.  The bytes past the buffer are handed to userspace\nthrough the rawmidi read path.\n\nurb-\u003eactual_length is not consulted either, so a short transfer leaves\nboth the type byte and the length byte at their previous values and the\nhandler acts on stale data.\n\nThe receiver URB is submitted from usb6fire_comm_init() at probe, so the\nread happens on plug with no user action; forwarding to userspace also\nneeds a MIDI input substream open, since usb6fire_midi_in_received()\nonly calls snd_rawmidi_receive() when rt-\u003ein is set.\n\nKASAN on 7.2.0-rc5 (arm64), single packet from an emulated device:\n\n  BUG: KASAN: slab-out-of-bounds in snd_rawmidi_receive\n  Read of size 255 at addr ffff000009f64682 by task bash/183\n   __asan_memcpy\n   snd_rawmidi_receive\n   usb6fire_midi_in_received [snd_usb_6fire]\n   usb6fire_comm_receiver_handler [snd_usb_6fire]\n  Allocated by task 11:\n   usb6fire_comm_init [snd_usb_6fire]\n   usb6fire_chip_probe [snd_usb_6fire]\n  The buggy address is located 2 bytes inside of\n   allocated 64-byte region [ffff000009f64680, ffff000009f646c0)\n\nReject the event when the length exceeds the bytes that follow the\nheader, and require the transfer to have delivered the header plus that\nmany bytes.  The receiver URB is submitted with a 64-byte\ntransfer_buffer_length, so a genuine device cannot deliver an event\nlonger than those 62 bytes and nothing valid is dropped.\n\nDiscovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e","modified":"2026-09-13T03:46:58.579078523Z","published":"2026-09-11T19:42:35.751Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80973.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/2a6f6fba3bd31d2e8c957fefa29156e35e5e75d5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/34816e2cfeabafb8eccf54687186ce25699e8363"},{"type":"WEB","url":"https://git.kernel.org/stable/c/466e911bbbbb779bb06337e35a286e5ca7af16b3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a478893b59e36cfe7d77a76b352f2db55502e879"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80973.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-80973"},{"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":"c6d43ba816d1cf1d125bfbfc938f2a28a87facf9"},{"fixed":"466e911bbbbb779bb06337e35a286e5ca7af16b3"},{"fixed":"2a6f6fba3bd31d2e8c957fefa29156e35e5e75d5"},{"fixed":"34816e2cfeabafb8eccf54687186ce25699e8363"},{"fixed":"a478893b59e36cfe7d77a76b352f2db55502e879"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80973.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"2.6.39"},{"fixed":"6.12.109"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.50"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-80973.json"}}],"schema_version":"1.9.0"}