CVE-2024-50163: bpf: Make sure internal and UAPI bpf_redirect flags don't overlap

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-11-07 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Make sure internal and UAPI bpf_redirect flags don't overlap The bpf_redirect_info is shared between the SKB and XDP redirect paths, and the two paths use the same numeric flag values in the ri->flags field (specifically, BPF_F_BROADCAST == BPF_F_NEXTHOP). This means that if skb bpf_redirect_neigh() is used with a non-NULL params argument and, subsequently, an XDP redirect is performed using the same bpf_redirect_info struct, the XDP path will get confused and end up crashing, which syzbot managed to trigger. With the stack-allocated bpf_redirect_info, the structure is no longer shared between the SKB and XDP paths, so the crash doesn't happen anymore. However, different code paths using identically-numbered flag values in the same struct field still seems like a bit of a mess, so this patch cleans that up by moving the flag definitions together and redefining the three flags in BPF_F_REDIRECT_INTERNAL to not overlap with the flags used for XDP. It also adds a BUILD_BUG_ON() check to make sure the overlap is not re-introduced by mistake.

Affected products

Linux kernel: from 5.14 before 5.15.170; from 5.16 before 6.1.115; from 6.2 before 6.6.59; from 6.7 before 6.11.6; 6.12-rc1, 6.12-rc2, 6.12-rc3 — fixed in 5.15.170, 6.1.115, 6.11.6, 6.6.59

How to fix

Upgrade to a fixed version: Linux kernel 5.15.170, 6.1.115, 6.11.6, 6.6.59. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2024-50163 or the next vulnerability affects your stack