CVE-2024-56678: powerpc/mm/fault: Fix kfence page fault reporting
First published: Sat Dec 28 2024(Updated: )
In the Linux kernel, the following vulnerability has been resolved: powerpc/mm/fault: Fix kfence page fault reporting copy_from_kernel_nofault() can be called when doing read of /proc/kcore. /proc/kcore can have some unmapped kfence objects which when read via copy_from_kernel_nofault() can cause page faults. Since *_nofault() functions define their own fixup table for handling fault, use that instead of asking kfence to handle such faults. Hence we search the exception tables for the nip which generated the fault. If there is an entry then we let the fixup table handler handle the page fault by returning an error from within ___do_page_fault(). This can be easily triggered if someone tries to do dd from /proc/kcore. eg. dd if=/proc/kcore of=/dev/null bs=1M Some example false negatives: =============================== BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0 Invalid read at 0xc0000000fdff0000: copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0 Use-after-free read at 0xc0000000fe050000 (in kfence-#2): copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| debian/linux | 5.10.223-1 5.10.226-1 6.1.123-1 6.1.128-1 6.12.12-1 6.12.15-1 |
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Reference Links
- https://git.kernel.org/stable/c/e0a470b5733c1fe068d5c58b0bb91ad539604bc6
- https://git.kernel.org/stable/c/4d2655754e94741b159aa807b72ea85518a65fd5
- https://git.kernel.org/stable/c/9ea8d8bf9b625e8ad3be6b0432aecdc549914121
- https://git.kernel.org/stable/c/7eaeb7a49b6d16640f9f3c9074c05175d74c710b
- https://git.kernel.org/stable/c/15f78d2c3d1452645bd8b9da909b0ca266f83c43
- https://git.kernel.org/stable/c/06dbbb4d5f7126b6307ab807cbf04ecfc459b933
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-56678
- https://nvd.nist.gov/vuln/detail/CVE-2024-56678
- https://launchpad.net/bugs/cve/CVE-2024-56678
- https://security-tracker.debian.org/tracker/CVE-2024-56678
- https://ubuntu.com/security/CVE-2024-56678
- https://git.kernel.org/linus/06dbbb4d5f7126b6307ab807cbf04ecfc459b933
Frequently Asked Questions
What is the severity of CVE-2024-56678?
CVE-2024-56678 is classified as a high severity vulnerability within the Linux kernel.
How do I fix CVE-2024-56678?
To resolve CVE-2024-56678, update your Linux kernel to the latest stable version recommended by your distribution.
What systems are affected by CVE-2024-56678?
CVE-2024-56678 affects all versions of the Linux kernel that include the faulty handling of kfence page fault reporting.
What is the potential impact of exploiting CVE-2024-56678?
Exploiting CVE-2024-56678 could lead to unauthorized access to memory contents, potentially exposing sensitive information.
When was CVE-2024-56678 discovered?
CVE-2024-56678 was reported and addressed in recent patches in 2024.
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