ghsa-q3m2-j43g-7966
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
comedi: check device's attached status in compat ioctls
Syzbot identified an issue [1] that crashes kernel, seemingly due to unexistent callback dev->get_valid_routes(). By all means, this should not occur as said callback must always be set to get_zero_valid_routes() in __comedi_device_postconfig().
As the crash seems to appear exclusively in i386 kernels, at least, judging from [1] reports, the blame lies with compat versions of standard IOCTL handlers. Several of them are modified and do not use comedi_unlocked_ioctl(). While functionality of these ioctls essentially copy their original versions, they do not have required sanity check for device's attached status. This, in turn, leads to a possibility of calling select IOCTLs on a device that has not been properly setup, even via COMEDI_DEVCONFIG.
Doing so on unconfigured devices means that several crucial steps are missed, for instance, specifying dev->get_valid_routes() callback.
Fix this somewhat crudely by ensuring device's attached status before performing any ioctls, improving logic consistency between modern and compat functions.
[1] Syzbot report: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... CR2: ffffffffffffffd6 CR3: 000000006c717000 CR4: 0000000000352ef0 Call Trace: get_valid_routes drivers/comedi/comedi_fops.c:1322 [inline] parse_insn+0x78c/0x1970 drivers/comedi/comedi_fops.c:1401 do_insnlist_ioctl+0x272/0x700 drivers/comedi/comedi_fops.c:1594 compat_insnlist drivers/comedi/comedi_fops.c:3208 [inline] comedi_compat_ioctl+0x810/0x990 drivers/comedi/comedi_fops.c:3273 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] ...
{
"affected": [],
"aliases": [
"CVE-2025-68257"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-12-16T15:15:55Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncomedi: check device\u0027s attached status in compat ioctls\n\nSyzbot identified an issue [1] that crashes kernel, seemingly due to\nunexistent callback dev-\u003eget_valid_routes(). By all means, this should\nnot occur as said callback must always be set to\nget_zero_valid_routes() in __comedi_device_postconfig().\n\nAs the crash seems to appear exclusively in i386 kernels, at least,\njudging from [1] reports, the blame lies with compat versions\nof standard IOCTL handlers. Several of them are modified and\ndo not use comedi_unlocked_ioctl(). While functionality of these\nioctls essentially copy their original versions, they do not\nhave required sanity check for device\u0027s attached status. This,\nin turn, leads to a possibility of calling select IOCTLs on a\ndevice that has not been properly setup, even via COMEDI_DEVCONFIG.\n\nDoing so on unconfigured devices means that several crucial steps\nare missed, for instance, specifying dev-\u003eget_valid_routes()\ncallback.\n\nFix this somewhat crudely by ensuring device\u0027s attached status before\nperforming any ioctls, improving logic consistency between modern\nand compat functions.\n\n[1] Syzbot report:\nBUG: kernel NULL pointer dereference, address: 0000000000000000\n...\nCR2: ffffffffffffffd6 CR3: 000000006c717000 CR4: 0000000000352ef0\nCall Trace:\n \u003cTASK\u003e\n get_valid_routes drivers/comedi/comedi_fops.c:1322 [inline]\n parse_insn+0x78c/0x1970 drivers/comedi/comedi_fops.c:1401\n do_insnlist_ioctl+0x272/0x700 drivers/comedi/comedi_fops.c:1594\n compat_insnlist drivers/comedi/comedi_fops.c:3208 [inline]\n comedi_compat_ioctl+0x810/0x990 drivers/comedi/comedi_fops.c:3273\n __do_compat_sys_ioctl fs/ioctl.c:695 [inline]\n __se_compat_sys_ioctl fs/ioctl.c:638 [inline]\n __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638\n do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]\n...",
"id": "GHSA-q3m2-j43g-7966",
"modified": "2025-12-16T15:30:47Z",
"published": "2025-12-16T15:30:47Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68257"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0de7d9cd07a2671fa6089173bccc0b2afe6b93ee"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/573b07d2e3d473ee7eb625ef87519922cf01168d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aac80e912de306815297a3b74f0426873ffa7dc3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f6e629dfe6f590091c662a87c9fcf118b1c1c7dc"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
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