CVE-2025-68257 (GCVE-0-2025-68257)
Vulnerability from cvelistv5
Published
2025-12-16 14:44
Modified
2025-12-16 14:44
Severity ?
Summary
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: <TASK> 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] ...
References
Impacted products
Vendor Product Version
Linux Linux Version: 3fbfd2223a271426509830e6340c386a1054cfad
Version: 3fbfd2223a271426509830e6340c386a1054cfad
Version: 3fbfd2223a271426509830e6340c386a1054cfad
Version: 3fbfd2223a271426509830e6340c386a1054cfad
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          "programFiles": [
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          "value": "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..."
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        "dateUpdated": "2025-12-16T14:44:59.535Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/0de7d9cd07a2671fa6089173bccc0b2afe6b93ee"
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    "cveId": "CVE-2025-68257",
    "datePublished": "2025-12-16T14:44:59.535Z",
    "dateReserved": "2025-12-16T13:41:40.267Z",
    "dateUpdated": "2025-12-16T14:44:59.535Z",
    "state": "PUBLISHED"
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    "nvd": "{\"cve\":{\"id\":\"CVE-2025-68257\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-16T15:15:55.100\",\"lastModified\":\"2025-12-18T15:08:06.237\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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...\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0de7d9cd07a2671fa6089173bccc0b2afe6b93ee\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/573b07d2e3d473ee7eb625ef87519922cf01168d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/aac80e912de306815297a3b74f0426873ffa7dc3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f6e629dfe6f590091c662a87c9fcf118b1c1c7dc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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