CVE-2025-40350: In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: RX, Fix generating skb from non-linear xdp_buff for striding RQ XDP p...

Description

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: RX, Fix generating skb from non-linear xdp_buff for striding RQ XDP programs can change the layout of an xdp_buff through bpf_xdp_adjust_tail() and bpf_xdp_adjust_head(). Therefore, the driver cannot assume the size of the linear data area nor fragments. Fix the bug in mlx5 by generating skb according to xdp_buff after XDP programs run. Currently, when handling multi-buf XDP, the mlx5 driver assumes the layout of an xdp_buff to be unchanged. That is, the linear data area continues to be empty and fragments remain the same. This may cause the driver to generate erroneous skb or triggering a kernel warning. When an XDP program added linear data through bpf_xdp_adjust_head(), the linear data will be ignored as mlx5e_build_linear_skb() builds an skb without linear data and then pull data from fragments to fill the linear data area. When an XDP program has shrunk the non-linear data through bpf_xdp_adjust_tail(), the delta passed to __pskb_pull_tail() may exceed the actual nonlinear data size and trigger the BUG_ON in it. To fix the issue, first record the original number of fragments. If the number of fragments changes after the XDP program runs, rewind the end fragment pointer by the difference and recalculate the truesize. Then, build the skb with the linear data area matching the xdp_buff. Finally, only pull data in if there is non-linear data and fill the linear part up to 256 bytes.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

0.17%

7.2th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= f52ac7028bec22e925c8fece4f21641eb13b4d6f, < 8b051d7f530e8a5237da242fbeafef02fec6b813; >= f52ac7028bec22e925c8fece4f21641eb13b4d6f, < cb9edd583e23979ee546981be963ad5f217e8b18; >= f52ac7028bec22e925c8fece4f21641eb13b4d6f, < f2557d7fa38e9475b38588f5c124476091480f53; >= f52ac7028bec22e925c8fece4f21641eb13b4d6f, < 87bcef158ac1faca1bd7e0104588e8e2956d10be
Linux	Linux	6.4

References

Timeline

Published: Dec 16, 2025
Last Modified: Jul 30, 2026
Status: Deferred

Frequently Asked Questions

What is CVE-2025-40350?

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: RX, Fix generating skb from non-linear xdp_buff for striding RQ XDP programs can change the layout of an xdp_buff through bpf_xdp_adjust_tail() and bpf_xdp_adjust_head(). Therefore, the driver cannot assume the size of the linear data area nor fragments. Fix the bug in mlx5 by generating skb according to xdp_buff after XDP programs run. Currently, when handling multi-buf XDP, the mlx5 driver assumes the layout of an xdp_buff to be unchanged. That is, the linear data area continues to be empty and fragments remain the same. This may cause the driver to generate erroneous skb or triggering a kernel warning. When an XDP program added linear data through bpf_xdp_adjust_head(), the linear data will be ignored as mlx5e_build_linear_skb() builds an skb without linear data and then pull data from fragments to fill the linear data area. When an XDP program has shrunk the non-linear data through bpf_xdp_adjust_tail(), the delta passed to __pskb_pull_tail() may exceed the actual nonlinear data size and trigger the BUG_ON in it. To fix the issue, first record the original number of fragments. If the number of fragments changes after the XDP program runs, rewind the end fragment pointer by the difference and recalculate the truesize. Then, build the skb with the linear data area matching the xdp_buff. Finally, only pull data in if there is non-linear data and fill the linear part up to 256 bytes.

How severe is CVE-2025-40350?

CVE-2025-40350 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.17% probability of exploitation in the next 30 days.

How do I fix CVE-2025-40350?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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