Description

In the Linux kernel, the following vulnerability has been resolved: efivarfs: force RO when remounting if SetVariable is not supported If SetVariable at runtime is not supported by the firmware we never assign a callback for that function. At the same time mount the efivarfs as RO so no one can call that. However, we never check the permission flags when someone remounts the filesystem as RW. As a result this leads to a crash looking like this: $ mount -o remount,rw /sys/firmware/efi/efivars $ efi-updatevar -f PK.auth PK [ 303.279166] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 [ 303.280482] Mem abort info: [ 303.280854] ESR = 0x0000000086000004 [ 303.281338] EC = 0x21: IABT (current EL), IL = 32 bits [ 303.282016] SET = 0, FnV = 0 [ 303.282414] EA = 0, S1PTW = 0 [ 303.282821] FSC = 0x04: level 0 translation fault [ 303.283771] user pgtable: 4k pages, 48-bit VAs, pgdp=000000004258c000 [ 303.284913] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000 [ 303.286076] Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP [ 303.286936] Modules linked in: qrtr tpm_tis tpm_tis_core crct10dif_ce arm_smccc_trng rng_core drm fuse ip_tables x_tables ipv6 [ 303.288586] CPU: 1 PID: 755 Comm: efi-updatevar Not tainted 6.3.0-rc1-00108-gc7d0c4695c68 #1 [ 303.289748] Hardware name: Unknown Unknown Product/Unknown Product, BIOS 2023.04-00627-g88336918701d 04/01/2023 [ 303.291150] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) [ 303.292123] pc : 0x0 [ 303.292443] lr : efivar_set_variable_locked+0x74/0xec [ 303.293156] sp : ffff800008673c10 [ 303.293619] x29: ffff800008673c10 x28: ffff0000037e8000 x27: 0000000000000000 [ 303.294592] x26: 0000000000000800 x25: ffff000002467400 x24: 0000000000000027 [ 303.295572] x23: ffffd49ea9832000 x22: ffff0000020c9800 x21: ffff000002467000 [ 303.296566] x20: 0000000000000001 x19: 00000000000007fc x18: 0000000000000000 [ 303.297531] x17: 0000000000000000 x16: 0000000000000000 x15: 0000aaaac807ab54 [ 303.298495] x14: ed37489f673633c0 x13: 71c45c606de13f80 x12: 47464259e219acf4 [ 303.299453] x11: ffff000002af7b01 x10: 0000000000000003 x9 : 0000000000000002 [ 303.300431] x8 : 0000000000000010 x7 : ffffd49ea8973230 x6 : 0000000000a85201 [ 303.301412] x5 : 0000000000000000 x4 : ffff0000020c9800 x3 : 00000000000007fc [ 303.302370] x2 : 0000000000000027 x1 : ffff000002467400 x0 : ffff000002467000 [ 303.303341] Call trace: [ 303.303679] 0x0 [ 303.303938] efivar_entry_set_get_size+0x98/0x16c [ 303.304585] efivarfs_file_write+0xd0/0x1a4 [ 303.305148] vfs_write+0xc4/0x2e4 [ 303.305601] ksys_write+0x70/0x104 [ 303.306073] __arm64_sys_write+0x1c/0x28 [ 303.306622] invoke_syscall+0x48/0x114 [ 303.307156] el0_svc_common.constprop.0+0x44/0xec [ 303.307803] do_el0_svc+0x38/0x98 [ 303.308268] el0_svc+0x2c/0x84 [ 303.308702] el0t_64_sync_handler+0xf4/0x120 [ 303.309293] el0t_64_sync+0x190/0x194 [ 303.309794] Code: ???????? ???????? ???????? ???????? (????????) [ 303.310612] ---[ end trace 0000000000000000 ]--- Fix this by adding a .reconfigure() function to the fs operations which we can use to check the requested flags and deny anything that's not RO if the firmware doesn't implement SetVariable at runtime.

Severity

 

CVSS Version 3.x CVSS Version 2.0

CVSS 3.x Severity and Metrics:

NIST: NVD

Base Score:  5.5 MEDIUM

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

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have published a CVSS score for this CVE based on publicly available information at the time of analysis. The CNA has not provided a score within the CVE List.

CVSS 2.0 Severity and Metrics:

NIST: NVD

Base Score: N/A

NVD assessment not yet provided.

NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: NVD Analysts have not published a CVSS score for this CVE at this time. NVD Analysts use publicly available information at the time of analysis to associate CVSS vector strings.

References to Advisories, Solutions, and Tools

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Hyperlink	Resource
https://git.kernel.org/stable/c/0049fe7e4a85849bdd778cdb72e51a791ff3d737	Patch
https://git.kernel.org/stable/c/0e8d2444168dd519fea501599d150e62718ed2fe	Patch
https://git.kernel.org/stable/c/2aa141f8bc580f8f9811dfe4e0e6009812b73826	Patch
https://git.kernel.org/stable/c/94c742324ed7e42c5bd6a9ed22e4ec6d764db4d8	Patch
https://git.kernel.org/stable/c/d4a714873db0866cc471521114eeac4a5072d548	Patch
https://git.kernel.org/stable/c/d4a9aa7db574a0da64307729cc031fb68597aa8b	Patch

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-476	NULL Pointer Dereference	NIST

Known Affected Software Configurations Switch to CPE 2.2

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Change History

2 change records found show changes

Initial Analysis by NIST 4/17/2024 4:05:08 PM

Action	Type	Old Value	New Value
Added	CPE Configuration		Record truncated, showing 500 of 547 characters. View Entire Change Record OR *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.8.0 up to (excluding) 5.10.209 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11.0 up to (excluding) 5.15.148 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16.0 up to (excluding) 6.1.75 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2.0 up to (excluding) 6.6.14 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions
Added	CVSS V3.1		NIST AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Added	CWE		NIST CWE-476
Changed	Reference Type	https://git.kernel.org/stable/c/0049fe7e4a85849bdd778cdb72e51a791ff3d737 No Types Assigned	https://git.kernel.org/stable/c/0049fe7e4a85849bdd778cdb72e51a791ff3d737 Patch
Changed	Reference Type	https://git.kernel.org/stable/c/0e8d2444168dd519fea501599d150e62718ed2fe No Types Assigned	https://git.kernel.org/stable/c/0e8d2444168dd519fea501599d150e62718ed2fe Patch
Changed	Reference Type	https://git.kernel.org/stable/c/2aa141f8bc580f8f9811dfe4e0e6009812b73826 No Types Assigned	https://git.kernel.org/stable/c/2aa141f8bc580f8f9811dfe4e0e6009812b73826 Patch
Changed	Reference Type	https://git.kernel.org/stable/c/94c742324ed7e42c5bd6a9ed22e4ec6d764db4d8 No Types Assigned	https://git.kernel.org/stable/c/94c742324ed7e42c5bd6a9ed22e4ec6d764db4d8 Patch
Changed	Reference Type	https://git.kernel.org/stable/c/d4a714873db0866cc471521114eeac4a5072d548 No Types Assigned	https://git.kernel.org/stable/c/d4a714873db0866cc471521114eeac4a5072d548 Patch
Changed	Reference Type	https://git.kernel.org/stable/c/d4a9aa7db574a0da64307729cc031fb68597aa8b No Types Assigned	https://git.kernel.org/stable/c/d4a9aa7db574a0da64307729cc031fb68597aa8b Patch

New CVE Received by NIST 2/23/2024 10:15:08 AM

Action	Type	Old Value	New Value
Added	Description		Record truncated, showing 500 of 3301 characters. View Entire Change Record In the Linux kernel, the following vulnerability has been resolved: efivarfs: force RO when remounting if SetVariable is not supported If SetVariable at runtime is not supported by the firmware we never assign a callback for that function. At the same time mount the efivarfs as RO so no one can call that. However, we never check the permission flags when someone remounts the filesystem as RW. As a result this leads to a crash looking like this: $ mount -o remount,rw /sys/firmware/efi/efivars
Added	Reference		Linux https://git.kernel.org/stable/c/0049fe7e4a85849bdd778cdb72e51a791ff3d737 [No types assigned]
Added	Reference		Linux https://git.kernel.org/stable/c/0e8d2444168dd519fea501599d150e62718ed2fe [No types assigned]
Added	Reference		Linux https://git.kernel.org/stable/c/2aa141f8bc580f8f9811dfe4e0e6009812b73826 [No types assigned]
Added	Reference		Linux https://git.kernel.org/stable/c/94c742324ed7e42c5bd6a9ed22e4ec6d764db4d8 [No types assigned]
Added	Reference		Linux https://git.kernel.org/stable/c/d4a714873db0866cc471521114eeac4a5072d548 [No types assigned]
Added	Reference		Linux https://git.kernel.org/stable/c/d4a9aa7db574a0da64307729cc031fb68597aa8b [No types assigned]