CVE-2026-81001
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: slip: fix use-after-free in sl_sync() slip_devs[] stores bare net_device pointers and takes no reference on them. sl_sync() and sl_alloc() walk that table from slip_open() under rtnl_lock(), while an entry is dropped by sl_free_netdev(), which sl_setup() installs as dev->priv_destructor. priv_destructor is called from netdev_run_todo(), which deliberately runs with the RTNL semaphore released so that it can sleep while waiting for the device refcount to drop: /* Snapshot list, allow later requests */ list_replace_init(&net_todo_list, &list); __rtnl_unlock(); ... if (dev->priv_destructor) dev->priv_destructor(dev); /* slip_devs[i] = NULL */ if (dev->needs_free_netdev) free_netdev(dev); ... /* Free network device */ kobject_put(&dev->dev.kobj); So rtnl_lock() does not serialise slip_open() against the teardown at all. sl_sync() can load slip_devs[i] while the entry is still published and dereference it after netdev_run_todo() has run the destructor and released the device: CPU0 (slip_open) CPU1 (slip_close) unregister_netdev() rtnl_unlock() netdev_run_todo() __rtnl_unlock() rtnl_lock() sl_sync() dev = slip_devs[i] priv_destructor(dev) slip_devs[i] = NULL kobject_put(&dev->dev.kobj) /* dev is freed */ sl = netdev_priv(dev) if (sl->tty || sl->leased) /* use-after-free */ BUG: KASAN: use-after-free in sl_sync drivers/net/slip/slip.c:730 [inline] BUG: KASAN: use-after-free in slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806 Read of size 1 at addr ffff8880712dac71 by task syz-executor.2/6506 CPU: 2 PID: 6506 Comm: syz-executor.2 Not tainted 6.1.134-syzkaller-00260-g0c8fc3469765 #0 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: sl_sync drivers/net/slip/slip.c:730 [inline] slip_open+0xef4/0x1210 drivers/net/slip/slip.c:806 tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433 tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564 tiocsetd drivers/tty/tty_io.c:2428 [inline] tty_ioctl+0x5f0/0x1530 drivers/tty/tty_io.c:2712 Allocated by task 6502: alloc_netdev_mqs+0x98/0xfe0 net/core/dev.c:10719 sl_alloc drivers/net/slip/slip.c:756 [inline] slip_open+0x36d/0x1210 drivers/net/slip/slip.c:817 tty_ldisc_open+0xa2/0x120 drivers/tty/tty_ldisc.c:433 tty_set_ldisc+0x324/0x720 drivers/tty/tty_ldisc.c:564 Freed by task 6497: device_release+0xa2/0x240 drivers/base/core.c:2507 kobject_put+0x179/0x280 lib/kobject.c:729 netdev_run_todo+0x6c8/0xef0 net/core/dev.c:10509 slip_close+0x166/0x1c0 drivers/net/slip/slip.c:906 tty_ldisc_close+0x113/0x1a0 drivers/tty/tty_ldisc.c:456 tty_ldisc_kill+0x94/0x160 drivers/tty/tty_ldisc.c:614 tty_ldisc_release+0xe3/0x2b0 drivers/tty/tty_ldisc.c:782 tty_release+0xbcc/0xe70 drivers/tty/tty_io.c:1860 Commit e58c19124189 ("slip: Fix use-after-free Read in slip_open") fixed a different source of stale entries - a device left in slip_devs[] after slip_open() freed it on the registration error path - and does not address this race, which is why the report survives it. Drop the entry from ndo_uninit instead. unregister_netdevice() calls ndo_uninit under RTNL, before the device is queued to netdev_run_todo(), so an entry that sl_sync() can still see while holding RTNL belongs to a device that cannot be freed until RTNL is dropped. sl_free_netdev() stays only for the slip_open() error path, where register_netdevice() may have failed before ndo_init and ndo_uninit is then not called either. Both running for the same device is harmless: the ---truncated---
View original CVE JSON
{
"id": "CVE-2026-81001",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-09-11T20:19:08.160",
"lastModified": "2026-10-19T09:17:33.150",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "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---"
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"drivers/net/slip/slip.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "045e307ac21fbd735b789d8817b21be4d8ead054",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "87398cdec8bdf84096a8af4dbccdb04f1972f32c",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "e93ace1f46177a4f7b5a8e5996606cdf77e1e890",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "70e20456bcbf7f3ae145bb96e5548f827a37c640",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "a235b20972bbd98ca1fb127d6269434edc607f19",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "486577db807891d0f964fdf13c1640c7f54b0ad1",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "d6f25e5bd777b05880da8673daf74a8419480545",
"versionType": "git",
"status": "affected"
},
{
"version": "5342b77c4123ba39f911d92a813295fb3bb21f69",
"lessThan": "2c4e7c42d77e78ad595dbb9e4b5886b58b45d89d",
"versionType": "git",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"drivers/net/slip/slip.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "2.6.32",
"status": "affected"
},
{
"version": "0",
"lessThan": "2.6.32",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.10.270",
"lessThanOrEqual": "5.10.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "5.15.221",
"lessThanOrEqual": "5.15.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.1.188",
"lessThanOrEqual": "6.1.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.157",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.109",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.50",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.4",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"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",
"attackVector": "LOCAL",
"attackComplexity": "LOW",
"privilegesRequired": "LOW",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"timestamp": "2026-10-16T19:22:06.585249Z",
"id": "CVE-2026-81001",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"version": "2.0.3"
}
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/045e307ac21fbd735b789d8817b21be4d8ead054",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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{
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{
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{
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{
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}