{ "schema_version": "1.6.1", "id": "RPI-CVE-2026-64588", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2026-64588" ], "published": "2026-08-06T07:14:03Z", "summary": "fuse-uring: fix data races on ring->ready", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfuse-uring: fix data races on ring->ready\n\nOn weakly-ordered architectures, the store to fiq->ops can be\nreordered past the store to ring->ready, allowing a CPU that sees\nring->ready == true via fuse_uring_ready() to dispatch requests\nthrough a stale fiq->ops pointer. Upgrade the store to\nsmp_store_release() and the load in fuse_uring_ready() to\nsmp_load_acquire() so that the preceding WRITE_ONCE(fiq->ops, ...)\nis visible to any CPU that observes ring->ready == true.\n\nAdditionally, fuse_uring_do_register() publishes ring->ready with\nWRITE_ONCE() but the fast-path check reads it with a plain load.\nThis is a marked-vs-unmarked access that KCSAN will flag. Wrap it in\nREAD_ONCE() to mark it without adding unnecessary ordering.\n\nAlso wrap the fc->ring load in fuse_uring_ready() in READ_ONCE() to\nprevent the compiler from reloading it between the NULL check and the\ndereference.", "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": [ "1:6.18.29-1+rpt1", "1:6.18.33-1+rpt1", "1:6.18.34-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.18.29+rpt-rpi-2712", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v6", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v7", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.29+rpt-rpi-v8-rt", "binary_version": "1:6.18.29-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-2712", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v6", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v7", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.33+rpt-rpi-v8-rt", "binary_version": "1:6.18.33-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-2712", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v6", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v7", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8", "binary_version": "1:6.18.34-1+rpt1" }, { "binary_name": "linux-image-6.18.34+rpt-rpi-v8-rt", "binary_version": "1:6.18.34-1+rpt1" } ] }, "database_specific": { "per_version": { "1:6.18.29-1+rpt1": { "linux_commit": "66318c5b5cd8145a662303af12ed39ac07eb27cc", "upstream_version": "6.18.29", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.39" }, "1:6.18.33-1+rpt1": { "linux_commit": "95b85bebbedcaedfa7ca79116ed38b7376fba412", "upstream_version": "6.18.33", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.39" }, "1:6.18.34-1+rpt1": { "linux_commit": "c8c7494100e99ee05b11aaa4f0588a223a63d1af", "upstream_version": "6.18.34", "assessment": "commit ancestry (strak rule)", "upstream_fixed": "6.18.39" } } } } ], "references": [ { "type": "ADVISORY", "url": "https://www.cve.org/CVERecord?id=CVE-2026-64588" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/b156bb9966972122b148acab8bdf415cdb8176a3" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/d01a09b442cb786cd44ccc7c84d57e2856d6737c" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/46725a0056c884cf58a6897f222892807327d82d" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-17T05:24:08Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 7.8, "cvss_v3_severity": "High", "scenario": "AV:L - The bug is reached locally by mounting FUSE with io-uring and submitting IORING_OP_URING_CMD registration while other local threads generate FUSE requests; no network protocol path invokes fuse_uring_ready() or fuse_uring_do_register().\nAC:L - The attacker controls both sides of the race by registering ring entries on /dev/fuse while concurrently issuing filesystem operations on the same mount, so the publish window on weakly ordered CPUs can be driven and retried without relying on victim state.\nPR:L - FUSE is FS_USERNS_MOUNT, so an ordinary user can create a user-namespace mount, open /dev/fuse, and enable FUSE_OVER_IO_URING without init-namespace root privileges.\nUI:N - The attacker can run both the FUSE daemon that registers io-uring queues and the client threads that generate requests on that mount, so no separate victim action is required.\nS:U - Impact is confined to the host kernel authority as a local FUSE/io-uring memory-safety failure, not a VM, IOMMU, or guest-to-host boundary escape.\nC:H - Missing acquire on ring->ready lets CPUs observe readiness while fiq->ops and related ring publication are stale, and the unfixed fc->ring reload in fuse_uring_ready() is a check-then-use UAF window against ring teardown, enabling disclosure of reclaimed kernel memory.\nI:H - Dispatching through inconsistent ops/ring state and the concurrent ring reload UAF allow writes and list/queue operations on stale or reallocated fuse_ring objects, which is exploitable for heap corruption and control-flow hijacking.\nA:H - The same races can NULL-dereference or use a freed fuse_ring in fuse_uring_task_to_queue()/fuse_uring_ready(), hang requests on the wrong queue path, and trigger WARN/oops or panic under panic_on_warn." } } }