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CVE-2025-39901

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 in

Published Oct 1, 2025 · updated Oct 14, 2026

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 " : ". For 'netdev_ops', this will be " : ". 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

Timeline

Detection, updates, and resolution for this record.

  1. Oct 1, 2025 · OSV.dev

    Detected

    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 ques

  2. Oct 14, 2026 · OSV.dev

    Fix available

    linux-aws-6.8 fixed in 6.8.0-1050.53~22.04.1; linux-azure-6.8 fixed in 6.8.0-1051.57~22.04.1; linux-azure-fde-6.8 fixed in 6.8.0-1058.65~22.04.1; linux-gcp-6.8 fixed in 6.8.0-1052.55~22.04.1

  3. Oct 14, 2026 · OSV.dev

    Updated

    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 ques

Affected

  • Ubuntu:16.04:LTS linux-hwe-edge4.8.0-28.30~16.04.1, 4.8.0-30.32~16.04.1, 4.8.0-32.34~16.04.1
  • Ubuntu:Pro:14.04:LTS linux3.11.0-12.19, 3.12.0-1.3, 3.12.0-2.5
  • Ubuntu:Pro:14.04:LTS linux-aws4.4.0-1002.2, 4.4.0-1003.3, 4.4.0-1005.5
  • Ubuntu:Pro:14.04:LTS linux-azure4.15.0-1023.24~14.04.1, 4.15.0-1030.31~14.04.1, 4.15.0-1031.32~14.04.1
  • Ubuntu:Pro:14.04:LTS linux-lts-xenial4.4.0-13.29~14.04.1, 4.4.0-14.30~14.04.2, 4.4.0-15.31~14.04.1
  • Ubuntu:Pro:16.04:LTS linux4.2.0-16.19, 4.2.0-17.21, 4.2.0-19.23
  • Ubuntu:Pro:16.04:LTS linux-aws4.4.0-1001.10, 4.4.0-1003.12, 4.4.0-1004.13
  • Ubuntu:Pro:16.04:LTS linux-aws-hwe4.15.0-1030.31~16.04.1, 4.15.0-1031.33~16.04.1, 4.15.0-1032.34~16.04.1
  • Ubuntu:Pro:16.04:LTS linux-azure4.11.0-1009.9, 4.11.0-1011.11, 4.11.0-1013.13
  • Ubuntu:Pro:16.04:LTS linux-gcp4.10.0-1004.4, 4.10.0-1006.6, 4.10.0-1007.7
  • Ubuntu:Pro:16.04:LTS linux-hwe4.8.0-36.36~16.04.1, 4.8.0-39.42~16.04.1, 4.8.0-41.44~16.04.1
  • Ubuntu:Pro:16.04:LTS linux-kvm4.4.0-1004.9, 4.4.0-1007.12, 4.4.0-1008.13

Sources

References