From: Jiri Olsa jolsa@kernel.org
stable inclusion from stable-v5.10.44 commit 584b2c7ce24450a7c687f976b54333607e14e058 bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=399 CVE: NA
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[ Upstream commit 31379397dcc364a59ce764fabb131b645c43e340 ]
We can't currently allow to attach functions with variable arguments. The problem is that we should save all the registers for arguments, which is probably doable, but if caller uses more than 6 arguments, we need stack data, which will be wrong, because of the extra stack frame we do in bpf trampoline, so we could crash.
Also currently there's malformed trampoline code generated for such functions at the moment as described in:
https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@kernel.org/
Signed-off-by: Jiri Olsa jolsa@kernel.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Acked-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20210505132529.401047-1-jolsa@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: wangruifeng 972063181@qq.com Reviewed-by: Jian Cheng <cj.chengjian(a)huawei.com> Signed-off-by: Wang ShaoBo bobo.shaobowang@huawei.com --- kernel/bpf/btf.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index ed7d02e8bc93..aaf2fbaa0cc7 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -4960,6 +4960,12 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, m->ret_size = ret;
for (i = 0; i < nargs; i++) { + if (i == nargs - 1 && args[i].type == 0) { + bpf_log(log, + "The function %s with variable args is unsupported.\n", + tname); + return -EINVAL; + } ret = __get_type_size(btf, args[i].type, &t); if (ret < 0) { bpf_log(log, @@ -4967,6 +4973,12 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, tname, i, btf_kind_str[BTF_INFO_KIND(t->info)]); return -EINVAL; } + if (ret == 0) { + bpf_log(log, + "The function %s has malformed void argument.\n", + tname); + return -EINVAL; + } m->arg_size[i] = ret; } m->nr_args = nargs;