{ "schema_version": "1.6.1", "id": "RPI-CVE-2024-35811", "modified": "2026-10-09T11:39:44Z", "upstream": [ "CVE-2024-35811" ], "published": "2024-05-17T13:23:58Z", "summary": "wifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach", "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: brcmfmac: Fix use-after-free bug in brcmf_cfg80211_detach\n\nThis is the candidate patch of CVE-2023-47233 :\nhttps://nvd.nist.gov/vuln/detail/CVE-2023-47233\n\nIn brcm80211 driver,it starts with the following invoking chain\nto start init a timeout worker:\n\n->brcmf_usb_probe\n ->brcmf_usb_probe_cb\n ->brcmf_attach\n ->brcmf_bus_started\n ->brcmf_cfg80211_attach\n ->wl_init_priv\n ->brcmf_init_escan\n ->INIT_WORK(&cfg->escan_timeout_work,\n\t\t brcmf_cfg80211_escan_timeout_worker);\n\nIf we disconnect the USB by hotplug, it will call\nbrcmf_usb_disconnect to make cleanup. The invoking chain is :\n\nbrcmf_usb_disconnect\n ->brcmf_usb_disconnect_cb\n ->brcmf_detach\n ->brcmf_cfg80211_detach\n ->kfree(cfg);\n\nWhile the timeout woker may still be running. This will cause\na use-after-free bug on cfg in brcmf_cfg80211_escan_timeout_worker.\n\nFix it by deleting the timer and canceling the worker in\nbrcmf_cfg80211_detach.\n\n[arend.vanspriel@broadcom.com: keep timer delete as is and cancel work just before free]", "severity": [ { "type": "CVSS_V3", "score": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H" } ], "affected": [ { "package": { "ecosystem": "Raspberry Pi OS:12", "name": "linux" }, "versions": [ "1:6.1.21-1+rpt1", "1:6.1.47-1+rpt2", "1:6.1.47-1+rpt4", "1:6.1.54-1+rpt2", "1:6.1.58-1+rpt2", "1:6.1.63-1+rpt1", "1:6.1.73-1+rpt1", "1:6.6.20-1+rpt1" ], "ecosystem_specific": { "binaries": [ { "binary_name": "linux-image-6.1.0-rpi1-rpi-v6", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l", "binary_version": "1:6.1.21-1+rpt1" }, { "binary_name": "linux-image-6.1.0-rpi1-rpi-v8", "binary_version": 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"https://git.kernel.org/stable/c/bacb8c3ab86dcd760c15903fcee58169bc3026aa" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/8c36205123dc57349b59b4f1a2301eb278cbc731" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/0b812f706fd7090be74812101114a0e165b36744" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/190794848e2b9d15de92d502b6ac652806904f5a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/6678a1e7d896c00030b31491690e8ddc9a90767a" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/0a7591e14a8da794d0b93b5d1c6254ccb23adacb" }, { "type": "FIX", "url": "https://git.kernel.org/stable/c/0f7352557a35ab7888bc7831411ec8a3cbe20d78" } ], "database_specific": { "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git", "upstream_modified": "2026-08-05T11:52:36Z", "severity": { "source": "kernel CNA", "cvss_v3_score": 8.8, "cvss_v3_severity": "High", "scenario": "AV:A - The vulnerable free/use race is in a WiFi driver and is reached automatically via the firmware-crash recovery path (`brcmf_fw_crashed()` \u2192 `bus_reset` work \u2192 `brcmf_pcie_reset`/`brcmf_sdio_bus_reset` \u2192 `brcmf_detach` \u2192 `brcmf_cfg80211_detach` \u2192 `kfree(cfg)`), while the escan timeout worker fires precisely because the firmware stopped responding mid-scan. An adjacent 802.11 attacker who induces a firmware halt (a well-documented failure mode of Broadcom fullmac firmware when fed malformed frames) while the station is doing its routine background scanning triggers both sides of the race over the air.\nAC:L - The attacker controls both halves of the race \u2014 the stalled scan that guarantees the 10 s escan timer expires and the firmware halt that drives the detach \u2014 and the window is wide because the worker blocks in `brcmf_fil_cmd_data_set()` waiting on a dead firmware while `brcmf_cfg80211_detach()` frees `escan_buf` and `cfg` in parallel. The attempt is freely repeatable, and heap grooming of the freed 65000-byte buffer and `cfg` slab is standard.\nPR:N - No local account or capability is needed on the affected system: the scan is issued by the normal background supplicant/NetworkManager activity, and the detach is performed autonomously by the driver's bus-reset recovery worker in response to a firmware halt. The originally reported USB-hotplug variant likewise requires no privileges.\nUI:N - Background scanning by wpa_supplicant/NetworkManager is continuous and automatic, and the `brcmf_fw_crashed()` \u2192 bus-reset \u2192 detach sequence runs entirely inside the kernel without any user action. No victim interaction is required at any point.\nS:U - The use-after-free corrupts kernel heap objects and is exploited within the kernel's own security authority, with no crossing of a hypervisor, IOMMU, or sandbox boundary. Impact remains confined to the kernel that owns the vulnerable component.\nC:H - After the free, `brcmf_inform_bss()` walks the dangling `escan_info.escan_buf` with a length/count taken from reallocated memory, giving controlled out-of-bounds reads, and `brcmf_inform_single_bss()` hands the resulting `notify_ie`/`notify_ielen` to `cfg80211_inform_bss_data()`, which copies that kernel memory into a BSS entry retrievable by userspace via nl80211. This is an arbitrary kernel-memory read with a direct exfiltration channel.\nI:H - The worker performs an indirect call through `cfg->d11inf.decchspec`, a function pointer loaded from the freed `cfg` object, giving control-flow hijack once the slab is reallocated with attacker-controlled data, and it also writes into freed memory (`bi->ctl_ch`, `cfg->scan_request = NULL`, `timer_delete_sync()` on a freed `timer_list`). Combined with the stale `ifp` and `scan_request` passed into further kernel calls, this yields write and code-execution primitives.\nA:H - Even without full exploitation, dereferencing the freed `cfg`, freed `escan_buf`, and freed `brcmf_if`, and running `timer_delete_sync()`/`cfg80211_scan_done()` on freed structures, reliably produces oopses, slab corruption, and kernel panic. The WiFi interface is destroyed and the system crashes." } } }