{"id":"CVE-2025-38250","title":"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","summary":"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 fil…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-416"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.4, < 6.6.97","linux_kernel >= 6.7, < 6.12.36","linux_kernel >= 6.13, < 6.15.5","linux_kernel = 6.16"],"patched":["linux_kernel 6.15.5"],"published":"2025-07-09","updated":"2026-10-15","sourceUpdated":"2026-10-15T22:18:36.813","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2025-38250","references":[{"url":"https://git.kernel.org/stable/c/0e5c144c557df910ab64d9c25d06399a9a735e65","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/1d6123102e9fbedc8d25bf4731da6d513173e49e","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/90dee0a0ff84fac8accd5be98412b3819f667149","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/bc0819a25e04cd68ef3568cfa51b63118fea39a7","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c56b177efce8b62798e4d96bdb9867106cb7c4a0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ce23b73f0f27e2dbeb81734a79db710f05aa33c6","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/dd4becd3fd4102696e1c15e6d260a1712a2d8685","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://cert-portal.siemens.com/productcert/html/ssa-784472.html","label":"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"}],"tags":["nvd","cve.org"],"epss":0.00182,"epssPercentile":0.07741,"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-15T21:48:58.439628Z"},"ingestedAt":"2026-10-15T03:30:12.816Z","slug":"CVE-2025-38250","body":"## Overview\n\nIn 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 <TASK>\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 </TASK>\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---\n\n## Affected\n\n- `linux_kernel >= 3.4, < 6.6.97`\n- `linux_kernel >= 6.7, < 6.12.36`\n- `linux_kernel >= 6.13, < 6.15.5`\n- `linux_kernel = 6.16`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 6.15.5`","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}