From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Andrii Nakryiko <andriin@fb.com>,
Alexei Starovoitov <ast@kernel.org>,
Sasha Levin <sashal@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 5.2 020/123] libbpf: sanitize VAR to conservative 1-byte INT
Date: Tue, 13 Aug 2019 22:09:04 -0400 [thread overview]
Message-ID: <20190814021047.14828-20-sashal@kernel.org> (raw)
In-Reply-To: <20190814021047.14828-1-sashal@kernel.org>
From: Andrii Nakryiko <andriin@fb.com>
[ Upstream commit 1d4126c4e1190d2f7d3f388552f9bd17ae0c64fc ]
If VAR in non-sanitized BTF was size less than 4, converting such VAR
into an INT with size=4 will cause BTF validation failure due to
violationg of STRUCT (into which DATASEC was converted) member size.
Fix by conservatively using size=1.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/libbpf.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3865a5d272514..77e14d9954796 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1044,8 +1044,13 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj)
if (!has_datasec && kind == BTF_KIND_VAR) {
/* replace VAR with INT */
t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
- t->size = sizeof(int);
- *(int *)(t+1) = BTF_INT_ENC(0, 0, 32);
+ /*
+ * using size = 1 is the safest choice, 4 will be too
+ * big and cause kernel BTF validation failure if
+ * original variable took less than 4 bytes
+ */
+ t->size = 1;
+ *(int *)(t+1) = BTF_INT_ENC(0, 0, 8);
} else if (!has_datasec && kind == BTF_KIND_DATASEC) {
/* replace DATASEC with STRUCT */
struct btf_var_secinfo *v = (void *)(t + 1);
--
2.20.1
next parent reply other threads:[~2019-08-14 2:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190814021047.14828-1-sashal@kernel.org>
2019-08-14 2:09 ` Sasha Levin [this message]
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 025/123] bpf: sockmap, sock_map_delete needs to use xchg Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 026/123] bpf: sockmap, synchronize_rcu before free'ing map Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 027/123] bpf: sockmap, only create entry if ulp is not already enabled Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 028/123] selftests/bpf: fix sendmsg6_prog on s390 Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 034/123] bpf: fix access to skb_shared_info->gso_segs Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 035/123] selftests/bpf: add another gso_segs access Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 036/123] libbpf: fix using uninitialized ioctl results Sasha Levin
2019-08-14 2:09 ` [PATCH AUTOSEL 5.2 042/123] libbpf: silence GCC8 warning about string truncation Sasha Levin
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