From: Eduard Zingerman <eddyz87@gmail.com> mainline inclusion from mainline-v6.13-rc3 commit 1a4607ffba35bf2a630aab299e34dd3f6e658d70 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ICAWEK CVE: CVE-2024-58237 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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. Signed-off-by: Eduard Zingerman <eddyz87@gmail.com> Link: https://lore.kernel.org/r/20241210041100.1898468-8-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Wang Liang <wangliang74@huawei.com> --- net/core/filter.c | 2 ++ tools/testing/selftests/bpf/progs/tc_bpf2bpf.c | 2 ++ 2 files changed, 4 insertions(+) diff --git a/net/core/filter.c b/net/core/filter.c index 2299f4b0ac89..f749ae30dc6d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -7951,6 +7951,8 @@ bool bpf_helper_changes_pkt_data(enum bpf_func_id func_id) case BPF_FUNC_xdp_adjust_head: case BPF_FUNC_xdp_adjust_meta: case BPF_FUNC_xdp_adjust_tail: + /* tail-called program could call any of the above */ + case BPF_FUNC_tail_call: return true; default: return false; diff --git a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c index d1a57f7d09bd..fe6249d99b31 100644 --- a/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/tc_bpf2bpf.c @@ -11,6 +11,8 @@ int subprog_tc(struct __sk_buff *skb) __sink(skb); __sink(ret); + /* let verifier know that 'subprog_tc' can change pointers to skb->data */ + bpf_skb_change_proto(skb, 0, 0); return ret; } -- 2.34.1