{"cve":"CVE-2026-68370","nvd":{"published":"2026-08-10T13:20:29.790","modified":"2026-08-19T17:20:46.603","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nusb: gadget: dummy_hcd: prevent fifo_req reuse during giveback\n\ndummy_hcd embeds a single shared usb_request (dum->fifo_req) that the\n\"emulated single-request FIFO\" fast-path in dummy_queue() reuses for\nsmall IN transfers: it copies the caller's request into it\n(req->req = *_req) and queues it, treating list_empty(&fifo_req.queue)\nas \"the slot is free\".\n\nThe completion side (dummy_timer/transfer/nuke/dummy_dequeue) follows\nthe standard pattern: list_del_init(&req->queue) unlinks the request,\nthen the lock is dropped and usb_gadget_giveback_request() invokes\nreq->complete().  But list_del_init() makes fifo_req.queue look empty\n*before* the completion callback returns, so a concurrent dummy_queue()\non another CPU sees the slot as free, reuses fifo_req and runs\nreq->req = *_req -- overwriting req->complete while dummy_timer is\nmid-calling it.  The indirect call then jumps to a clobbered pointer,\ncausing a general protection fault / page fault in dummy_timer\n(syzkaller extid faf3a6cf579fc65591ca).  The clobbering write is an\nin-bounds memcpy on a live shared object, so KASAN cannot flag it.\n\nAdd a fifo_req_busy bit covering the shared request's whole lifetime:\nset it in dummy_queue() when the FIFO fast-path takes fifo_req (making\nit the fast-path guard, replacing the list_empty(&fifo_req.queue)\ntest), and clear it after the completion callback has returned, via a\ndummy_giveback() helper used at all four gadget-request giveback\nsites.  The shared slot can no longer be reused until its completion\ncallback has finished.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/16a685172abc9233728830e27d26ffa778975b51","https://git.kernel.org/stable/c/3cab0e5498d0fbb21fe1a9181f7bda9a844a697e","https://git.kernel.org/stable/c/67b589d09a96882d56842dced5698ed8dd06ce45","https://git.kernel.org/stable/c/95f30a21612cc65761c58ba044b1767699437317","https://git.kernel.org/stable/c/d5e5cd3654d2b5359a12ea6586120f05b28634ee"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:47:54.990491175+00:00"},"epss":{"cve":"CVE-2026-68370","score":0.00138,"percentile":0.03206,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}