vulnerability
Debian: CVE-2024-50163: linux, linux-6.1 -- security update
| Severity | CVSS | Published | Added | Modified |
|---|---|---|---|---|
| 5 | (AV:L/AC:L/Au:S/C:N/I:N/A:C) | Nov 7, 2024 | Nov 11, 2024 | Jan 30, 2025 |
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.
Solutions
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