From 257af63d7f84f0672aa6a24b5511871f00741f19 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 31 Jan 2020 16:03:14 -0800 Subject: bpf: Fix modifier skipping logic Fix the way modifiers are skipped while walking pointers. Otherwise second level dereferences of 'const struct foo *' will be rejected by the verifier. Fixes: 9e15db66136a ("bpf: Implement accurate raw_tp context access via BTF") Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200201000314.261392-1-ast@kernel.org --- kernel/bpf/btf.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 8c9d8f266bef..805c43b083e9 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3931,6 +3931,7 @@ again: if (btf_type_is_ptr(mtype)) { const struct btf_type *stype; + u32 id; if (msize != size || off != moff) { bpf_log(log, @@ -3939,12 +3940,9 @@ again: return -EACCES; } - stype = btf_type_by_id(btf_vmlinux, mtype->type); - /* skip modifiers */ - while (btf_type_is_modifier(stype)) - stype = btf_type_by_id(btf_vmlinux, stype->type); + stype = btf_type_skip_modifiers(btf_vmlinux, mtype->type, &id); if (btf_type_is_struct(stype)) { - *next_btf_id = mtype->type; + *next_btf_id = id; return PTR_TO_BTF_ID; } } -- cgit v1.2.3-59-g8ed1b