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Linux KernelOperating system · Linux

CVE-2024-26867

MEDIUM · 5.5 CVSS v3.1 Published 2024-04-17
Fix available
A fix is available. Upgrade to 6.7.11 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: comedi: comedi_8255: Correct error in subdevice initialization The refactoring done in commit 5c57b1ccecc7 ("comedi: comedi_8255: Rework subdevice initialization functions") to the initialization of the io field of struct subdev_8255_private broke all cards using the drivers/comedi/drivers/comedi_8255.c module. Prior to 5c57b1ccecc7, __subdev_8255_init() initialized the io field in the newly allocated struct subdev_8255_private to the non-NULL callback given to the function, otherwise it used a flag parameter to select between subdev_8255_mmio and subdev_8255_io. The refactoring removed that logic and the flag, as subdev_8255_mm_init() and subdev_8255_io_init() now explicitly pass subdev_8255_mmio and subdev_8255_io respectively to __subdev_8255_init(), only __subdev_8255_init() never sets spriv->io to the supplied callback. That spriv->io is NULL leads to a later BUG: BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 0 P4D 0 Oops: 0010 [#1] SMP PTI CPU: 1 PID: 1210 Comm: systemd-udevd Not tainted 6.7.3-x86_64 #1 Hardware name: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffffa3f1c02d7b78 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff91f847aefd00 RCX: 000000000000009b RDX: 0000000000000003 RSI: 0000000000000001 RDI: ffff91f840f6fc00 RBP: ffff91f840f6fc00 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 000000000000005f R12: 0000000000000000 R13: 0000000000000000 R14: ffffffffc0102498 R15: ffff91f847ce6ba8 FS: 00007f72f4e8f500(0000) GS:ffff91f8d5c80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 000000010540e000 CR4: 00000000000406f0 Call Trace: <TASK> ? __die_body+0x15/0x57 ? page_fault_oops+0x2ef/0x33c ? insert_vmap_area.constprop.0+0xb6/0xd5 ? alloc_vmap_area+0x529/0x5ee ? exc_page_fault+0x15a/0x489 ? asm_exc_page_fault+0x22/0x30 __subdev_8255_init+0x79/0x8d [comedi_8255] pci_8255_auto_attach+0x11a/0x139 [8255_pci] comedi_auto_config+0xac/0x117 [comedi] ? __pfx___driver_attach+0x10/0x10 pci_device_probe+0x88/0xf9 really_probe+0x101/0x248 __driver_probe_device+0xbb/0xed driver_probe_device+0x1a/0x72 __driver_attach+0xd4/0xed bus_for_each_dev+0x76/0xb8 bus_add_driver+0xbe/0x1be driver_register+0x9a/0xd8 comedi_pci_driver_register+0x28/0x48 [comedi_pci] ? __pfx_pci_8255_driver_init+0x10/0x10 [8255_pci] do_one_initcall+0x72/0x183 do_init_module+0x5b/0x1e8 init_module_from_file+0x86/0xac __do_sys_finit_module+0x151/0x218 do_syscall_64+0x72/0xdb entry_SYSCALL_64_after_hwframe+0x6e/0x76 RIP: 0033:0x7f72f50a0cb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 8b 0d 47 71 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffd47e512d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 0000562dd06ae070 RCX: 00007f72f50a0cb9 RDX: 0000000000000000 RSI: 00007f72f52d32df RDI: 000000000000000e RBP: 0000000000000000 R08: 00007f72f5168b20 R09: 0000000000000000 R10: 0000000000000050 R11: 0000000000000246 R12: 00007f72f52d32df R13: 0000000000020000 R14: 0000562dd06785c0 R15: 0000562dcfd0e9a8 </TASK> Modules linked in: 8255_pci(+) comedi_8255 comedi_pci comedi intel_gtt e100(+) acpi_cpufreq rtc_cmos usbhid CR2: 0000000000000000 ---[ end trace 0000000000000000 ]--- RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. RSP: 0018:ffffa3f1c02d7b78 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffff91f847aefd00 RCX: 000000000000009b RDX: 0000000000000003 RSI: 0000000000000001 RDI: ffff91f840f6fc00 RBP: ffff91f840f6fc00 R08: 0000000000000000 R09: 0000000000000001 R10: 0000000000000000 R11: 000000000000005f R12: 0000000000000000 R13: 0000000000000000 R14: ffffffffc0102498 R15: ffff91f847ce6ba8 FS: ---truncated---

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-476

The code follows a pointer that is null, crashing the process. An attacker who can reliably trigger it turns the crash into a denial of service. The fix is checking for null before use and handling the failure path gracefully.

General guidance for the null pointer dereference class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.7, < 6.7.11= 6.8

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.7.11 or later
Fixed in 6.7.11
Vendor patch git.kernel.org →
Recommended fix High confidence

Kernel 6.7.11 or later; or Kernel 6.8.1 or later (any stable release beyond the affected versions)

  1. Identify the current running kernel version using `uname -r`
  2. If running kernel 6.7.x: plan to upgrade to kernel version 6.7.11 or later
  3. If running kernel 6.8.x: plan to upgrade to a kernel version greater than 6.8 that includes the fix (e.g., 6.8.1 or later stable release)
  4. Apply the vendor patch commit 4a825457a45d8debc46ab8cba57d47462411710d if upgrading is not immediately feasible
  5. After patching/rebooting, verify the comedi and comedi_8255 modules load without NULL pointer dereference errors
Caveat Kernel upgrades may require rebooting the system and could have compatibility implications with custom kernel modules or specific hardware drivers

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $2,850. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-26867 in production — separate from our analysis above.

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