{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-38250", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:23.997Z", "datePublished": "2025-07-09T10:42:30.294Z", "dateUpdated": "2026-08-05T12:00:43.317Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:00:43.317Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: hci_core: Fix use-after-free in vhci_flush()\n\nsyzbot reported use-after-free in vhci_flush() without repro. [0]\n\nFrom the splat, a thread close()d a vhci file descriptor while\nits device was being used by iotcl() on another thread.\n\nOnce the last fd refcnt is released, vhci_release() calls\nhci_unregister_dev(), hci_free_dev(), and kfree() for struct\nvhci_data, which is set to hci_dev->dev->driver_data.\n\nThe problem is that there is no synchronisation after unlinking\nhdev from hci_dev_list in hci_unregister_dev(). There might be\nanother thread still accessing the hdev which was fetched before\nthe unlink operation.\n\nWe can use SRCU for such synchronisation.\n\nLet's run hci_dev_reset() under SRCU and wait for its completion\nin hci_unregister_dev().\n\nAnother option would be to restore hci_dev->destruct(), which was\nremoved in commit 587ae086f6e4 (\"Bluetooth: Remove unused\nhci-destruct cb\"). However, this would not be a good solution, as\nwe should not run hci_unregister_dev() while there are in-flight\nioctl() requests, which could lead to another data-race KCSAN splat.\n\nNote that other drivers seem to have the same problem, for exmaple,\nvirtbt_remove().\n\n[0]:\nBUG: KASAN: slab-use-after-free in skb_queue_empty_lockless include/linux/skbuff.h:1891 [inline]\nBUG: KASAN: slab-use-after-free in skb_queue_purge_reason+0x99/0x360 net/core/skbuff.c:3937\nRead of size 8 at addr ffff88807cb8d858 by task syz.1.219/6718\n\nCPU: 1 UID: 0 PID: 6718 Comm: syz.1.219 Not tainted 6.16.0-rc1-syzkaller-00196-g08207f42d3ff #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025\nCall Trace:\n \n dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:408 [inline]\n print_report+0xd2/0x2b0 mm/kasan/report.c:521\n kasan_report+0x118/0x150 mm/kasan/report.c:634\n skb_queue_empty_lockless include/linux/skbuff.h:1891 [inline]\n skb_queue_purge_reason+0x99/0x360 net/core/skbuff.c:3937\n skb_queue_purge include/linux/skbuff.h:3368 [inline]\n vhci_flush+0x44/0x50 drivers/bluetooth/hci_vhci.c:69\n hci_dev_do_reset net/bluetooth/hci_core.c:552 [inline]\n hci_dev_reset+0x420/0x5c0 net/bluetooth/hci_core.c:592\n sock_do_ioctl+0xd9/0x300 net/socket.c:1190\n sock_ioctl+0x576/0x790 net/socket.c:1311\n vfs_ioctl fs/ioctl.c:51 [inline]\n __do_sys_ioctl fs/ioctl.c:907 [inline]\n __se_sys_ioctl+0xf9/0x170 fs/ioctl.c:893\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7fcf5b98e929\nCode: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007fcf5c7b9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\nRAX: ffffffffffffffda RBX: 00007fcf5bbb6160 RCX: 00007fcf5b98e929\nRDX: 0000000000000000 RSI: 00000000400448cb RDI: 0000000000000009\nRBP: 00007fcf5ba10b39 R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 0000000000000000 R14: 00007fcf5bbb6160 R15: 00007ffd6353d528\n \n\nAllocated by task 6535:\n kasan_save_stack mm/kasan/common.c:47 [inline]\n kasan_save_track+0x3e/0x80 mm/kasan/common.c:68\n poison_kmalloc_redzone mm/kasan/common.c:377 [inline]\n __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394\n kasan_kmalloc include/linux/kasan.h:260 [inline]\n __kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4359\n kmalloc_noprof include/linux/slab.h:905 [inline]\n kzalloc_noprof include/linux/slab.h:1039 [inline]\n vhci_open+0x57/0x360 drivers/bluetooth/hci_vhci.c:635\n misc_open+0x2bc/0x330 drivers/char/misc.c:161\n chrdev_open+0x4c9/0x5e0 fs/char_dev.c:414\n do_dentry_open+0xdf0/0x1970 fs/open.c:964\n vfs_open+0x3b/0x340 fs/open.c:1094\n do_open fs/namei.c:3887 [inline]\n path_openat+0x2ee5/0x3830 fs/name\n---truncated---" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Although this is the Bluetooth subsystem, the vulnerable path is not reachable from over-the-air traffic — it requires a local `ioctl(HCIDEVRESET)` on an AF_BLUETOOTH HCI socket raced against a local `close()` of the transport fd (or driver removal). Both sides of the race are local syscalls.\nAC:L - The attacker controls both racing threads (close of the vhci fd vs. the HCIDEVRESET ioctl) and the window is large, spanning the full `hci_dev_close_sync()`/`hci_dev_open_sync()` command-sync sequence inside `hci_dev_do_reset()`. Failed attempts are harmless and can be repeated indefinitely until the race is won.\nPR:L - `HCIDEVRESET` is gated on `capable(CAP_NET_ADMIN)`, a capability held by non-root service accounts such as bluetoothd and Android's Bluetooth process rather than requiring full init-namespace root, and this repo consistently scores CAP_NET_ADMIN-gated Bluetooth mgmt/ioctl bugs as PR:L. The free side additionally needs no privilege at all when supplied by ordinary transport-driver teardown (btusb/hci_ldisc/virtio_bt unregister).\nUI:N - The attacker drives both the reset ioctl and the device teardown from its own threads with no victim participation. No user action of any kind is needed.\nS:U - The use-after-free corrupts kernel heap memory and yields kernel-privilege compromise within the same security authority. No VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a slab use-after-free on a `kmalloc-1k` object; `skb_queue_purge_reason()` reads the freed `sk_buff_head` and dereferences pointers taken from it, so an attacker who reclaims the slot obtains an arbitrary kernel-memory read primitive and full disclosure of kernel memory.\nI:H - The UAF is read *and* write: `skb_queue_splice_init()` writes back into the freed object and `kfree_skb()` is invoked on attacker-reclaimable pointers, while `vhci_send_frame()` performs `skb_queue_tail()` into freed memory. That combination gives a controlled-free and linked-list-write primitive suitable for control-flow hijacking and privilege escalation.\nA:H - Even without successful heap grooming, purging a freed skb queue and freeing garbage pointers reliably corrupts the slab allocator and panics the kernel. The attacker can trigger it repeatedly for a persistent denial of service." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/bluetooth/hci_core.h", "net/bluetooth/hci_core.c" ], "versions": [ { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "dd4becd3fd4102696e1c15e6d260a1712a2d8685", "status": "affected", "versionType": "git" }, { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "90dee0a0ff84fac8accd5be98412b3819f667149", "status": "affected", "versionType": "git" }, { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "c56b177efce8b62798e4d96bdb9867106cb7c4a0", "status": "affected", "versionType": "git" }, { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "bc0819a25e04cd68ef3568cfa51b63118fea39a7", "status": "affected", "versionType": "git" }, { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "ce23b73f0f27e2dbeb81734a79db710f05aa33c6", "status": "affected", "versionType": "git" }, { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "0e5c144c557df910ab64d9c25d06399a9a735e65", "status": "affected", "versionType": "git" }, { "version": "bf18c7118cf83ad4b9aa476354b4a06bcb9d0c4f", "lessThan": "1d6123102e9fbedc8d25bf4731da6d513173e49e", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/bluetooth/hci_core.h", "net/bluetooth/hci_core.c" ], "versions": [ { "version": "3.4", "status": "affected" }, { "version": "0", "lessThan": "3.4", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.209", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.167", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.97", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.36", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.15.5", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "5.10.259" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "5.15.209" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "6.1.167" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "6.6.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "6.12.36" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "6.15.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4", "versionEndExcluding": "6.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/dd4becd3fd4102696e1c15e6d260a1712a2d8685" }, { "url": "https://git.kernel.org/stable/c/90dee0a0ff84fac8accd5be98412b3819f667149" }, { "url": "https://git.kernel.org/stable/c/c56b177efce8b62798e4d96bdb9867106cb7c4a0" }, { "url": "https://git.kernel.org/stable/c/bc0819a25e04cd68ef3568cfa51b63118fea39a7" }, { "url": "https://git.kernel.org/stable/c/ce23b73f0f27e2dbeb81734a79db710f05aa33c6" }, { "url": "https://git.kernel.org/stable/c/0e5c144c557df910ab64d9c25d06399a9a735e65" }, { "url": "https://git.kernel.org/stable/c/1d6123102e9fbedc8d25bf4731da6d513173e49e" } ], "title": "Bluetooth: hci_core: Fix use-after-free in vhci_flush()", "x_generator": { "engine": "bippy-1.2.0" } } } }