CVE-2024-58237
In the Linux kernel, the following vulnerability has been resolved:
bpf: consider that tail calls invalidate packet pointers
Tail-called programs could execute any of the helpers that invalidate packet pointers. Hence, conservatively assume that each tail call invalidates packet pointers.
Making the change in bpf_helper_changes_pkt_data() automatically makes use of check_cfg() logic that computes 'changes_pkt_data' effect for global sub-programs, such that the following program could be rejected:
int tail_call(struct __sk_buff *sk)
{
bpf_tail_call_static(sk, &jmp_table, 0);
return 0;
}
SEC("tc")
int not_safe(struct __sk_buff *sk)
{
int *p = (void *)(long)sk->data;
... make p valid ...
tail_call(sk);
*p = 42; /* this is unsafe */
...
}
The tc_bpf2bpf.c:subprog_tc() needs change: mark it as a function that can invalidate packet pointers. Otherwise, it can't be freplaced with tailcall_freplace.c:entry_freplace() that does a tail call.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 5.6 | 6.6.90 |
| linux / linux_kernel | 6.7 | 6.12.9 |
| linux / linux_kernel | 6.13-rc1 | 6.13-rc1.x |
| linux / linux_kernel | 6.13-rc2 | 6.13-rc2.x |
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