CVE-2021-47559 net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()

What is CVE-2021-47559?

CVE-2021-47559 is a high-severity vulnerability in Linux kernel, published on 24 May 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

In the Linux kernel, the following vulnerability has been resolved:

net/smc: Fix NULL pointer dereferencing in smc_vlan_by_tcpsk()

Coverity reports a possible NULL dereferencing problem:

in smc_vlan_by_tcpsk(): 6. returned_null: netdev_lower_get_next returns NULL (checked 29 out of 30 times). 7. var_assigned: Assigning: ndev = NULL return value from netdev_lower_get_next. 1623 ndev = (struct net_device *)netdev_lower_get_next(ndev, &lower); CID 1468509 (#1 of 1): Dereference null return value (NULL_RETURNS) 8. dereference: Dereferencing a pointer that might be NULL ndev when calling is_vlan_dev. 1624 if (is_vlan_dev(ndev)) {

Remove the manual implementation and use netdev_walk_all_lower_dev() to iterate over the lower devices. While on it remove an obsolete function parameter comment.

Weakness: CWE-476

Which versions are affected by CVE-2021-47559?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2021-47559?

Apply the vendor's patch.

Is CVE-2021-47559 being exploited?

There is no known exploitation of CVE-2021-47559 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• How this page is made

Also known as DEBIAN-CVE-2021-47559, UBUNTU-CVE-2021-47559.