{"id":"DEBIAN-CVE-2026-80970","details":"In the Linux kernel, the following vulnerability has been resolved:  ALSA: FCP: do not copy out an uninitialised init response  fcp_ioctl_init() allocates its response buffer with kmalloc() and copies the whole buffer back to userspace:  \tbuf_size = init.step0_resp_size + init.step2_resp_size;  \tvoid *resp __free(kfree) = \t\tkmalloc(buf_size, GFP_KERNEL); \t... \tif (copy_to_user(arg-\u003eresp, resp, buf_size)) \t\treturn -EFAULT;  Nothing clears the buffer, and the only writer of its leading step0_resp_size bytes is the step-0 control transfer:  \terr = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), \t\tFCP_USB_REQ_STEP0, \t\tUSB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN, \t\t0, private-\u003ebInterfaceNumber, \t\tstep0_resp, private-\u003estep0_resp_size); \tif (err \u003c 0) \t\treturn err;  usb_fill_control_urb() does not set URB_SHORT_NOT_OK, so a short or zero-length data stage completes with status 0 and snd_usb_ctl_msg() returns a small actual_length.  The only check is err \u003c 0, so a short transfer is accepted as success.  snd_usb_ctl_msg() copies the full size back unconditionally:  \tbuf = kmemdup(data, size, GFP_KERNEL); \t... \tmemcpy(data, buf, size);  Bytes the device never wrote are therefore restored into resp unchanged and copied to userspace.  step0_resp_size and step2_resp_size are each validated only to 1..255, so the caller also picks the slab cache, from kmalloc-8 up to kmalloc-512.  On 7.2.0-rc5 (arm64), device answering step 0 with a zero-length data stage, s0 = s2 = 255:    # init_on_alloc off, no spray   step0 window [0,255): nonzero=94/255   000: 00 80 60 06 00 00 ff ff 18 00 00 00 57 01 ea 01   010: 08 78 22 13 00 00 ff ff a8 c4 5f 80 00 80 ff ff    # same kernel, kmalloc-512 pre-seeded with an 8-byte tag   step0 window [0,255): nonzero=219/255  tagbytes=232    # identical run, init_on_alloc=1   step0 window [0,255): nonzero=0/255  tagbytes=0    # all three runs   step2 window [255,510): device words matched=62/62  a8 c4 5f 80 00 80 ff ff is the little-endian kernel text address ffff8000805fc4a8.  The step-2 window is unaffected, so the disclosure is exactly the step-0 region.  Zero the buffer, and require the step-0 transfer to deliver the full step0_resp_size bytes so a short data stage is reported as an error.  Discovered by XBOW, triaged by Baul Lee \u003cbaul.lee@xbow.com\u003e","modified":"2026-09-23T04:00:19.493622072Z","published":"2026-09-11T20:19:03.090Z","upstream":["CVE-2026-80970"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-80970"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.2.6-1"}]}],"versions":["6.12.100-1","6.12.101-1","6.12.105-1","6.12.107-1","6.12.38-1","6.12.41-1","6.12.43-1","6.12.43-1~bpo12+1","6.12.48-1","6.12.57-1","6.12.57-1~bpo12+1","6.12.63-1","6.12.63-1~bpo12+1","6.12.69-1","6.12.69-1~bpo12+1","6.12.73-1","6.12.73-1~bpo12+1","6.12.74-1","6.12.74-2","6.12.74-2~bpo12+1","6.12.85-1","6.12.85-1~bpo12+1","6.12.86-1","6.12.86-1~bpo12+1","6.12.88-1","6.12.88-1~bpo12+1","6.12.90-1","6.12.90-1~bpo12+1","6.12.90-2","6.12.90-2~bpo12+1","6.12.94-1","6.12.94-1~bpo12+1","6.12.95-1","6.12.95-1~bpo12+1","6.12.96-1","6.13.10-1~exp1","6.13.11-1~exp1","6.13.2-1~exp1","6.13.3-1~exp1","6.13.4-1~exp1","6.13.5-1~exp1","6.13.6-1~exp1","6.13.7-1~exp1","6.13.8-1~exp1","6.13.9-1~exp1","6.13~rc6-1~exp1","6.13~rc7-1~exp1","6.14.3-1~exp1","6.14.5-1~exp1","6.14.6-1~exp1","6.15-1~exp1","6.15.1-1~exp1","6.15.2-1~exp1","6.15.3-1~exp1","6.15.4-1~exp1","6.15.5-1~exp1","6.15.6-1~exp1","6.15~rc7-1~exp1","6.16-1~exp1","6.16.1-1~exp1","6.16.10-1","6.16.11-1","6.16.12-1","6.16.12-1~bpo13+1","6.16.12-2","6.16.3-1","6.16.3-1~bpo13+1","6.16.5-1","6.16.6-1","6.16.7-1","6.16.8-1","6.16.9-1","6.16~rc7-1~exp1","6.17.10-1","6.17.11-1","6.17.12-1","6.17.13-1","6.17.13-1~bpo13+1","6.17.2-1~exp1","6.17.5-1~exp1","6.17.6-1","6.17.7-1","6.17.7-2","6.17.8-1","6.17.8-1~bpo13+1","6.17.9-1","6.18.1-1~exp1","6.18.10-1","6.18.12-1","6.18.12-1~bpo13+1","6.18.13-1","6.18.14-1","6.18.15-1","6.18.15-1~bpo13+1","6.18.2-1~exp1","6.18.3-1","6.18.5-1","6.18.5-1~bpo13+1","6.18.8-1","6.18.9-1","6.18.9-1~bpo13+1","6.18~rc4-1~exp1","6.18~rc4-1~exp2","6.18~rc5-1~exp1","6.18~rc6-1~exp1","6.18~rc7-1~exp1","6.19-1~exp1","6.19.10-1","6.19.10-1~bpo13+1","6.19.11-1","6.19.11-1~bpo13+1","6.19.12-1","6.19.13-1","6.19.13-1~bpo13+1","6.19.14-1","6.19.14-1~bpo13+1","6.19.2-1~exp1","6.19.3-1~exp1","6.19.4-1~exp1","6.19.5-1~exp1","6.19.6-1","6.19.6-2","6.19.6-2~bpo13+1","6.19.8-1","6.19.8-1~bpo13+1","6.19~rc4-1~exp1","6.19~rc5-1~exp1","6.19~rc6-1~exp1","6.19~rc7-1~exp1","6.19~rc8-1~exp1","7.0-1~exp1","7.0.1-1~exp1","7.0.10-1","7.0.10-1~bpo13+1","7.0.12-1","7.0.12-2","7.0.12-2~bpo13+1","7.0.13-1","7.0.13-1~bpo13+1","7.0.14-1","7.0.3-1","7.0.4-1","7.0.4-1~bpo13+1","7.0.7-1","7.0.7-1~bpo13+1","7.0.9-1","7.0.9-1~bpo13+1","7.1.1-1~exp1","7.1.10-1","7.1.12-1","7.1.13-1","7.1.2-1~exp1","7.1.3-1","7.1.3-1+sunvdc","7.1.3-1~bpo13+1","7.1.4-1","7.1.5-1","7.1.6-1","7.1.7-1","7.1.7-1~bpo13+1","7.1.8-1","7.1.8-1~bpo13+1","7.1.8-2","7.1.9-1","7.1.9-1+sparc64","7.1~rc2-1~exp1","7.1~rc3-1~exp1","7.1~rc4-1~exp1","7.1~rc4-1~exp2","7.1~rc5-1~exp1","7.1~rc7-1~exp1","7.2.2-1~exp1","7.2.3-1~exp1","7.2~rc3-1~exp1","7.2~rc5-1~exp1","7.2~rc7-1~exp1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-80970.json"}}],"schema_version":"1.9.0"}