UBUNTU-CVE-2024-50163
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.
02 / AFFECTED SOFTWARE
Affected packages
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51 explicit affected versions
11 explicit affected versions
15 explicit affected versions
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03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/09d88791c7cd888d5195c84733caf9183dcfbd16
- https://git.kernel.org/stable/c/09d88791c7cd888d5195c84733caf9183dcfbd16
- https://git.kernel.org/stable/c/0fca5ed4be8e8bfbfb9bd97845af596bab7192d3
- https://git.kernel.org/stable/c/314dbee9fe4f5cee36435465de52c988d7caa466
- https://git.kernel.org/stable/c/4e1e428533845d48828bd3875c0e92e8565b9962
- https://git.kernel.org/stable/c/cec288e05ceac9a0d3a3a1fd279534b11844c826
- https://ubuntu.com/security/CVE-2024-50163
- https://ubuntu.com/security/notices/USN-7276-1
- https://ubuntu.com/security/notices/USN-7277-1
- https://ubuntu.com/security/notices/USN-7288-1
- https://ubuntu.com/security/notices/USN-7288-2
- https://ubuntu.com/security/notices/USN-7289-1
- https://ubuntu.com/security/notices/USN-7289-2
- https://ubuntu.com/security/notices/USN-7289-3
- https://ubuntu.com/security/notices/USN-7289-4
- https://ubuntu.com/security/notices/USN-7291-1
- https://ubuntu.com/security/notices/USN-7305-1
- https://ubuntu.com/security/notices/USN-7308-1
- https://ubuntu.com/security/notices/USN-7310-1
- https://ubuntu.com/security/notices/USN-7331-1
- https://ubuntu.com/security/notices/USN-7388-1
- https://ubuntu.com/security/notices/USN-7389-1
- https://ubuntu.com/security/notices/USN-7390-1
- https://ubuntu.com/security/notices/USN-7449-1
- https://ubuntu.com/security/notices/USN-7449-2
- https://ubuntu.com/security/notices/USN-7450-1
- https://ubuntu.com/security/notices/USN-7451-1
- https://ubuntu.com/security/notices/USN-7452-1
- https://ubuntu.com/security/notices/USN-7453-1
- https://ubuntu.com/security/notices/USN-7458-1
- https://ubuntu.com/security/notices/USN-7468-1
- https://ubuntu.com/security/notices/USN-7523-1
- https://ubuntu.com/security/notices/USN-7524-1
- https://www.cve.org/CVERecord?id=CVE-2024-50163