DEBIAN-CVE-2025-39986

In the Linux kernel, the following vulnerability has been resolved: can: sun4i_can: 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, sun4ican_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN frame. This can result in a buffer overflow. The driver will consume cf->len as-is with no further checks on this line: dlc = cf->len; Here, cf->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 a couple line below when doing: for (i = 0; i < dlc; i++) writel(cf->data[i], priv->base + (dreg + i * 4)); 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.

References

https://security-tracker.debian.org/tracker/CVE-2025-39986

Affected packages

Debian:12 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source&distro=bookworm

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

6.1.158-1

Affected versions

6.*

6.1.27-1

6.1.37-1

6.1.38-1

6.1.38-2~bpo11+1

6.1.38-2

6.1.38-3

6.1.38-4~bpo11+1

6.1.38-4

6.1.52-1

6.1.55-1~bpo11+1

6.1.55-1

6.1.64-1

6.1.66-1

6.1.67-1

6.1.69-1~bpo11+1

6.1.69-1

6.1.76-1~bpo11+1

6.1.76-1

6.1.82-1

6.1.85-1

6.1.90-1~bpo11+1

6.1.90-1

6.1.94-1~bpo11+1

6.1.94-1

6.1.98-1

6.1.99-1

6.1.106-1

6.1.106-2

6.1.106-3

6.1.112-1

6.1.115-1

6.1.119-1

6.1.123-1

6.1.124-1

6.1.128-1

6.1.129-1

6.1.133-1

6.1.135-1

6.1.137-1

6.1.139-1

6.1.140-1

6.1.147-1

6.1.148-1

6.1.153-1

Ecosystem specific

{
    "urgency":  "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-39986.json"

Debian:13 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source&distro=trixie

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

6.12.57-1

Affected versions

6.*

6.12.38-1

6.12.41-1

6.12.43-1~bpo12+1

6.12.43-1

6.12.48-1

6.12.57-1~bpo12+1

Ecosystem specific

{
    "urgency":  "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-39986.json"

Debian:14 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source&distro=forky

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Fixed

6.16.10-1

Affected versions

6.*

6.12.38-1

6.12.41-1

6.12.43-1~bpo12+1

6.12.43-1

6.12.48-1

6.12.57-1~bpo12+1

6.12.57-1

6.12.63-1~bpo12+1

6.12.63-1

6.12.69-1~bpo12+1

6.12.69-1

6.12.73-1~bpo12+1

6.12.73-1

6.12.74-1

6.12.74-2~bpo12+1

6.12.74-2

6.12.85-1~bpo12+1

6.12.85-1

6.12.86-1~bpo12+1

6.12.86-1

6.12.88-1~bpo12+1

6.12.88-1

6.12.90-1~bpo12+1

6.12.90-1

6.12.90-2~bpo12+1

6.12.90-2

6.12.94-1~bpo12+1

6.12.94-1

6.12.95-1~bpo12+1

6.12.95-1

6.12.96-1

6.12.100-1

6.12.101-1

6.12.105-1

6.12.107-1

6.13~rc6-1~exp1

6.13~rc7-1~exp1

6.13.2-1~exp1

6.13.3-1~exp1

6.13.4-1~exp1

6.13.5-1~exp1

6.13.6-1~exp1

6.13.7-1~exp1

6.13.8-1~exp1

6.13.9-1~exp1

6.13.10-1~exp1

6.13.11-1~exp1

6.14.3-1~exp1

6.14.5-1~exp1

6.14.6-1~exp1

6.15~rc7-1~exp1

6.15-1~exp1

6.15.1-1~exp1

6.15.2-1~exp1

6.15.3-1~exp1

6.15.4-1~exp1

6.15.5-1~exp1

6.15.6-1~exp1

6.16~rc7-1~exp1

6.16-1~exp1

6.16.1-1~exp1

6.16.3-1~bpo13+1

6.16.3-1

6.16.5-1

6.16.6-1

6.16.7-1

6.16.8-1

6.16.9-1

Ecosystem specific

{
    "urgency":  "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2025-39986.json"