{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-90022", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-90022" ], "published": "2026-09-16T10:32:03Z", "summary": "usb: gadget: f_midi2: fix use-after-free in string attribute show path", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: f_midi2: fix use-after-free in string attribute show path\n\nf_midi2_opts_str_show() takes the string lock internally, but its\ncallers dereference the opts->info. pointer before calling it,\noutside the lock. This races with f_midi2_opts_str_store(), which\nfrees the old string under opts->lock when the attribute is written\nconcurrently, the show path can read a pointer that gets freed\nbefore the lock inside str_show() is even taken.\n\nChange f_midi2_opts_str_show() to take a pointer to the string field,\nmatching the existing pattern in f_midi2_opts_str_store(), and\ndereference it only after the lock is held. Update all three callers\n(iface_name, block name, and the EP string option macro) accordingly.", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:13", "name": "linux" }, "versions": [ "1:6.18.39-1+rpt1", "1:6.18.50-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.39+rpt-rpi-2712", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v6", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v7", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.39+rpt-rpi-v8-rt", "binary_version": "1:6.18.39-1+rpt1" }, { "binary_name": "linux-image-6.18.50+rpt-rpi-2712", "binary_version": "1:6.18.50-1+rpt1" }, { "binary_name": "linux-image-6.18.50+rpt-rpi-v6", "binary_version": "1:6.18.50-1+rpt1" }, { "binary_name": "linux-image-6.18.50+rpt-rpi-v7", "binary_version": "1:6.18.50-1+rpt1" }, { "binary_name": "linux-image-6.18.50+rpt-rpi-v8", "binary_version": "1:6.18.50-1+rpt1" }, { "binary_name": "linux-image-6.18.50+rpt-rpi-v8-rt", "binary_version": "1:6.18.50-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.39-1+rpt1": { "linux_commit": "60ea684a8ace97bb0db1a16e20753bdd6ab371ff", "upstream_version": "6.18.39", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.51" }, "1:6.18.50-1+rpt1": { "linux_commit": "cff533aec2fa601846766b32ff57204e0a61bed7", "upstream_version": "6.18.50", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.51" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-90022" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/f9bdf4c4f6410a1dfafafa383a0e21069372657f" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d11f3300b39e2daad2f0d9d66ddcc39a156cb594" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/e89e30f0b5d3004fe5955250bd8b04f3733e32ce" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/49fab5e1bdb205c36c965d0e9677bc40d282d3a2" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/fed0aa7c6eaedc6c0d4e362fc91724aa47be4a7b" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-09-17T09:33:32Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The UAF is reached by concurrent local read/write of midi2 configfs string attributes (iface_name, ep_name, product_id, block name) under /sys/kernel/config/usb_gadget//functions/midi2.*; no USB host packets, cable, or UDC bind are required, matching other gadget configfs bugs scored Local rather than Physical.\nAC:L - The attacker controls both sides by opening the same attribute on two fds (configfs serializes only per-fd) and racing show against store; store kfree()s the prior kstrndup string under opts->lock while show already holds the stale pointer, and the function need not be bound (store fails only if refcnt != 0).\nPR:L - gadgets_make(), function_make(), and the midi2 show/store handlers perform no capable() check; access is gated only by configfs DAC, and Android/embedded USB gadget HALs routinely chown /sys/kernel/config/usb_gadget to non-root system or daemon accounts.\nUI:N - The attacker creates the midi2 function instance and performs the concurrent attribute read/write themselves; configfs is typically already mounted at /sys/kernel/config, and no victim mount, cable plug, or other-user action is required.\nS:U - The use-after-free of the configfs kstrndup string corrupts kernel heap within the same host kernel security authority; this is not a VM escape, sandbox breakout, or IOMMU/DMA boundary bypass.\nC:H - Callers load opts->info. outside the lock, then f_midi2_opts_str_show() scnprintfs that pointer after a concurrent store kfree()d it; reclaiming the kmalloc object lets the attacker control the bytes copied to userspace, a UAF disclosure primitive.\nI:H - The same UAF of the kstrndup string, with store spraying attacker-chosen size and content into the same slab, is a classic heap use-after-free that can be converted into overlapping objects, arbitrary write, and control-flow hijack.\nA:H - scnprintf() of the freed string after kfree() reliably produces a KASAN slab-use-after-free oops or kernel panic, which the attacker can retrigger with further concurrent show/store loops." } } }