CVE-2025-39987
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-15

Last updated on: 2025-10-16

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: can: hi311x: populate ndo_change_mtu() to prevent buffer overflow Sending an PF_PACKET allows to bypass the CAN framework logic and to directly reach the xmit() function of a CAN driver. The only check which is performed by the PF_PACKET framework is to make sure that skb->len fits the interface's MTU. Unfortunately, because the sun4i_can driver does not populate its net_device_ops->ndo_change_mtu(), it is possible for an attacker to configure an invalid MTU by doing, for example: $ ip link set can0 mtu 9999 After doing so, the attacker could open a PF_PACKET socket using the ETH_P_CANXL protocol: socket(PF_PACKET, SOCK_RAW, htons(ETH_P_CANXL)) to inject a malicious CAN XL frames. For example: struct canxl_frame frame = { .flags = 0xff, .len = 2048, }; The CAN drivers' xmit() function are calling can_dev_dropped_skb() to check that the skb is valid, unfortunately under above conditions, the malicious packet is able to go through can_dev_dropped_skb() checks: 1. the skb->protocol is set to ETH_P_CANXL which is valid (the function does not check the actual device capabilities). 2. the length is a valid CAN XL length. And so, hi3110_hard_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN frame. The driver will consume frame->len as-is with no further checks. This can result in a buffer overflow later on in hi3110_hw_tx() on this line: memcpy(buf + HI3110_FIFO_EXT_DATA_OFF, frame->data, frame->len); Here, frame->len corresponds to the flags field of the CAN XL frame. In our previous example, we set canxl_frame->flags to 0xff. Because the maximum expected length is 8, a buffer overflow of 247 bytes occurs! Populate net_device_ops->ndo_change_mtu() to ensure that the interface's MTU can not be set to anything bigger than CAN_MTU. By fixing the root cause, this prevents the buffer overflow.
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Meta Information
Published
2025-10-15
Last Modified
2025-10-16
Generated
2026-05-07
AI Q&A
2025-10-15
EPSS Evaluated
2026-05-05
NVD
CVE-2025-39987
EUVD
EUVD-2025-34585
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 5.15.160 (inc) to 5.16 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's CAN (Controller Area Network) driver hi311x. It occurs because the driver does not properly implement the ndo_change_mtu() function, allowing an attacker to set an invalid MTU (Maximum Transmission Unit) size. By doing so, the attacker can send malicious CAN XL frames through a PF_PACKET socket that bypass normal CAN framework checks. The hi3110 driver misinterprets these frames and copies data without proper length validation, leading to a buffer overflow.


How can this vulnerability impact me? :

This vulnerability can lead to a buffer overflow in the hi3110 CAN driver, which may cause memory corruption. Such memory corruption can potentially be exploited to crash the system, cause denial of service, or execute arbitrary code with kernel privileges, depending on the attacker's goals and environment.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

You can detect this vulnerability by checking if any CAN network interface has an invalid MTU set above the CAN_MTU limit. For example, use the command: ip link show can0 to check the MTU value of the CAN interface. If the MTU is set to an unusually high value (e.g., 9999), it indicates a potential exploitation attempt. Additionally, monitoring for PF_PACKET sockets opened with the ETH_P_CANXL protocol could indicate attempts to inject malicious CAN XL frames.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves ensuring that the net_device_ops->ndo_change_mtu() is properly populated to prevent setting the MTU above the CAN_MTU limit. Until a patch is applied, avoid allowing MTU changes on CAN interfaces to values larger than CAN_MTU. You should also restrict or monitor the creation of PF_PACKET sockets with the ETH_P_CANXL protocol to prevent injection of malicious CAN XL frames.


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