i40e: remove read access to debugfs files

Summary

CVE	CVE-2025-39901
State	PUBLISHED
Assigner	Linux
Source Priority	CVE Program / NVD first with legacy fallback
Published	2025-10-01 08:15:32 UTC
Updated	2026-08-19 17:18:35 UTC
Description	In the Linux kernel, the following vulnerability has been resolved: i40e: remove read access to debugfs files The 'command' and 'netdev_ops' debugfs files are a legacy debugging interface supported by the i40e driver since its early days by commit 02e9c290814c ("i40e: debugfs interface"). Both of these debugfs files provide a read handler which is mostly useless, and which is implemented with questionable logic. They both use a static 256 byte buffer which is initialized to the empty string. In the case of the 'command' file this buffer is literally never used and simply wastes space. In the case of the 'netdev_ops' file, the last command written is saved here. On read, the files contents are presented as the name of the device followed by a colon and then the contents of their respective static buffer. For 'command' this will always be "<device>: ". For 'netdev_ops', this will be "<device>: <last command written>". But note the buffer is shared between all devices operated by this module. At best, it is mostly meaningless information, and at worse it could be accessed simultaneously as there doesn't appear to be any locking mechanism. We have also recently received multiple reports for both read functions about their use of snprintf and potential overflow that could result in reading arbitrary kernel memory. For the 'command' file, this is definitely impossible, since the static buffer is always zero and never written to. For the 'netdev_ops' file, it does appear to be possible, if the user carefully crafts the command input, it will be copied into the buffer, which could be large enough to cause snprintf to truncate, which then causes the copy_to_user to read beyond the length of the buffer allocated by kzalloc. A minimal fix would be to replace snprintf() with scnprintf() which would cap the return to the number of bytes written, preventing an overflow. A more involved fix would be to drop the mostly useless static buffers, saving 512 bytes and modifying the read functions to stop needing those as input. Instead, lets just completely drop the read access to these files. These are debug interfaces exposed as part of debugfs, and I don't believe that dropping read access will break any script, as the provided output is pretty useless. You can find the netdev name through other more standard interfaces, and the 'netdev_ops' interface can easily result in garbage if you issue simultaneous writes to multiple devices at once. In order to properly remove the i40e_dbg_netdev_ops_buf, we need to refactor its write function to avoid using the static buffer. Instead, use the same logic as the i40e_dbg_command_write, with an allocated buffer. Update the code to use this instead of the static buffer, and ensure we free the buffer on exit. This fixes simultaneous writes to 'netdev_ops' on multiple devices, and allows us to remove the now unused static buffer along with removing the read access.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

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

Problem Types: CWE-125 | CWE-125 CWE-125 Out-of-bounds Read

Version	Source	Type	Score	Severity	Vector
3.1	[email protected]	Primary	7.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`
3.1	ADP	DECLARED	7.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`
3.1	134c704f-9b21-4f2e-91b3-4a467353bcc0	Secondary	7.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H`

CVSS v3.1 Breakdown

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

High

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

NVD Known Affected Configurations (CPE 2.3)

Type	Vendor	Product	Version	Update	Edition	Language
Operating System	Linux	Linux Kernel	All	All	All	All

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Linux	Linux	affected 02e9c290814cc143ceccecb14eac3e7a05da745e 6fd8b30a5cb84d74015bc651799d1ab1e047946c git	Not specified
CNA	Linux	Linux	affected 02e9c290814cc143ceccecb14eac3e7a05da745e ef40d9411469306e524e7887c51b709377e6ef65 git	Not specified
CNA	Linux	Linux	affected 02e9c290814cc143ceccecb14eac3e7a05da745e 70d3dad7d5ad077965d7a63eed1942b7ba49bfb4 git	Not specified
CNA	Linux	Linux	affected 02e9c290814cc143ceccecb14eac3e7a05da745e 7d190963b80f4cd99d7008615600aa7cc993c6ba git	Not specified
CNA	Linux	Linux	affected 02e9c290814cc143ceccecb14eac3e7a05da745e 9fcdb1c3c4ba134434694c001dbff343f1ffa319 git	Not specified
CNA	Linux	Linux	affected 3.12	Not specified
CNA	Linux	Linux	unaffected 3.12 semver	Not specified
CNA	Linux	Linux	unaffected 6.1.183 6.1.* semver	Not specified
CNA	Linux	Linux	unaffected 6.6.148 6.6.* semver	Not specified
CNA	Linux	Linux	unaffected 6.12.46 6.12.* semver	Not specified
CNA	Linux	Linux	unaffected 6.16.6 6.16.* semver	Not specified
CNA	Linux	Linux	unaffected 6.17 * original_commit_for_fix	Not specified

References

Reference	Source	Link	Tags
git.kernel.org/stable/c/ef40d9411469306e524e7887c51b709377e6ef65	416baaa9-dc9f-4396-8d5f-8c081fb06d67	git.kernel.org
git.kernel.org/stable/c/70d3dad7d5ad077965d7a63eed1942b7ba49bfb4	416baaa9-dc9f-4396-8d5f-8c081fb06d67	git.kernel.org	Patch
git.kernel.org/stable/c/9fcdb1c3c4ba134434694c001dbff343f1ffa319	416baaa9-dc9f-4396-8d5f-8c081fb06d67	git.kernel.org	Patch
git.kernel.org/stable/c/6fd8b30a5cb84d74015bc651799d1ab1e047946c	416baaa9-dc9f-4396-8d5f-8c081fb06d67	git.kernel.org
git.kernel.org/stable/c/7d190963b80f4cd99d7008615600aa7cc993c6ba	416baaa9-dc9f-4396-8d5f-8c081fb06d67	git.kernel.org	Patch
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

There are currently no legacy QID mappings associated with this CVE.