{"cve":"CVE-2026-81001","nvd":{"published":"2026-09-11T20:19:08.160","modified":"2026-10-19T09:17:33.150","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nslip: fix use-after-free in sl_sync()\n\nslip_devs[] stores bare net_device pointers and takes no reference on\nthem.  sl_sync() and sl_alloc() walk that table from slip_open() under\nrtnl_lock(), while an entry is dropped by sl_free_netdev(), which\nsl_setup() installs as dev->priv_destructor.\n\npriv_destructor is called from netdev_run_todo(), which deliberately\nruns with the RTNL semaphore released so that it can sleep while waiting\nfor the device refcount to drop:\n\n\t/* Snapshot list, allow later requests */\n\tlist_replace_init(&net_todo_list, &list);\n\n\t__rtnl_unlock();\n\t...\n\t\tif (dev->priv_destructor)\n\t\t\tdev->priv_destructor(dev);\t/* slip_devs[i] = NULL */\n\t\tif (dev->needs_free_netdev)\n\t\t\tfree_netdev(dev);\n\t\t...\n\t\t/* Free network device */\n\t\tkobject_put(&dev->dev.kobj);\n\nSo rtnl_lock() does not serialise slip_open() against the teardown at\nall.  sl_sync() can load slip_devs[i] while the entry is still published\nand dereference it after netdev_run_todo() has run the destructor and\nreleased the device:\n\n  CPU0 (slip_open)                 CPU1 (slip_close)\n                                   unregister_netdev()\n                                     rtnl_unlock()\n                                       netdev_run_todo()\n                                         __rtnl_unlock()\n  rtnl_lock()\n  sl_sync()\n    dev = slip_devs[i]\n                                         priv_destructor(dev)\n                                           slip_devs[i] = NULL\n                                         kobject_put(&dev->dev.kobj)\n                                           /* dev is freed */\n    sl = netdev_priv(dev)\n    if (sl->tty || sl->leased)     /* use-after-free */\n\n  BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:730 [inline]\n  BUG: KASAN: use-after-free in slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806\n  Read of size 1 at addr ffff8880712dac71 by task syz-executor.2/6506\n\n  CPU: 2 PID: 6506 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00260-g0c8fc3469765 #0\n  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014\n  Call Trace:\n   sl_sync drivers/net/slip/slip.c:730 [inline]\n   slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806\n   tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433\n   tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564\n   tiocsetd drivers/tty/tty_io.c:2428 [inline]\n   tty_ioctl+0x5f0/0x1530 drivers/tty/tty_io.c:2712\n\n  Allocated by task 6502:\n   alloc_netdev_mqs+0x98/0xfe0 net/core/dev.c:10719\n   sl_alloc drivers/net/slip/slip.c:756 [inline]\n   slip_open+0x36d/0x1210 drivers/net/slip/slip.c:817\n   tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433\n   tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564\n\n  Freed by task 6497:\n   device_release+0xa2/0x240 drivers/base/core.c:2507\n   kobject_put+0x179/0x280 lib/kobject.c:729\n   netdev_run_todo+0x6c8/0xef0 net/core/dev.c:10509\n   slip_close+0x166/0x1c0 drivers/net/slip/slip.c:906\n   tty_ldisc_close+0x113/0x1a0 drivers/tty/tty_ldisc.c:456\n   tty_ldisc_kill+0x94/0x160 drivers/tty/tty_ldisc.c:614\n   tty_ldisc_release+0xe3/0x2b0 drivers/tty/tty_ldisc.c:782\n   tty_release+0xbcc/0xe70 drivers/tty/tty_io.c:1860\n\nCommit e58c19124189 (\"slip: Fix use-after-free Read in slip_open\") fixed\na different source of stale entries - a device left in slip_devs[] after\nslip_open() freed it on the registration error path - and does not\naddress this race, which is why the report survives it.\n\nDrop the entry from ndo_uninit instead.  unregister_netdevice() calls\nndo_uninit under RTNL, before the device is queued to netdev_run_todo(),\nso an entry that sl_sync() can still see while holding RTNL belongs to a\ndevice that cannot be freed until RTNL is dropped.  sl_free_netdev()\nstays only for the slip_open() error path, where register_netdevice()\nmay have failed before ndo_init and ndo_uninit is then not called\neither.  Both running for the same device is harmless: the\n---truncated---","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/045e307ac21fbd735b789d8817b21be4d8ead054","https://git.kernel.org/stable/c/2c4e7c42d77e78ad595dbb9e4b5886b58b45d89d","https://git.kernel.org/stable/c/486577db807891d0f964fdf13c1640c7f54b0ad1","https://git.kernel.org/stable/c/70e20456bcbf7f3ae145bb96e5548f827a37c640","https://git.kernel.org/stable/c/87398cdec8bdf84096a8af4dbccdb04f1972f32c"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-81001","score":0.00164,"percentile":0.05555,"date":"2026-10-25"},"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."]}