CVE-2025-40350
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-12-16

Last updated on: 2025-12-18

Assigner: kernel.org

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.
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Meta Information
Published
2025-12-16
Last Modified
2025-12-18
Generated
2026-05-07
AI Q&A
2025-12-16
EPSS Evaluated
2026-05-05
NVD
CVE-2025-40350
EUVD
EUVD-2025-203637
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability involves the Linux kernel's mlx5 network driver mishandling the layout changes of xdp_buff structures made by XDP programs. XDP programs can modify the linear and non-linear data areas of xdp_buff using bpf_xdp_adjust_tail() and bpf_xdp_adjust_head(). The mlx5 driver incorrectly assumes the layout remains unchanged, which can lead to generating erroneous socket buffers (skb) or triggering kernel warnings and errors. The fix involves properly tracking changes in fragment counts and sizes after XDP programs run, and correctly building skb with the updated linear data area.


How can this vulnerability impact me? :

This vulnerability can cause the mlx5 driver to generate incorrect socket buffers or trigger kernel warnings and errors, potentially leading to network packet processing issues or kernel instability. This may affect system reliability and network performance on systems using the affected driver with XDP programs.


What immediate steps should I take to mitigate this vulnerability?

To mitigate this vulnerability, update the Linux kernel to a version where the mlx5 driver has been fixed to properly handle changes in xdp_buff layout caused by XDP programs. This fix ensures that skb generation accounts for linear data and fragment changes, preventing kernel warnings or errors.


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