From: Alexei Starovoitov <ast@kernel.org>
To: "David S . Miller" <davem@davemloft.net>
Cc: <daniel@iogearbox.net>, <netdev@vger.kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf] bpf/verifier: disallow pointer subtraction
Date: Wed, 12 Sep 2018 14:06:10 -0700 [thread overview]
Message-ID: <20180912210610.829166-1-ast@kernel.org> (raw)
Subtraction of pointers was accidentally allowed for unpriv programs
by commit 82abbf8d2fc4. Revert that part of commit.
Fixes: 82abbf8d2fc4 ("bpf: do not allow root to mangle valid pointers")
Reported-by: Jann Horn <jannh@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
kernel/bpf/verifier.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 92246117d2b0..bb07e74b34a2 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3163,7 +3163,7 @@ static int adjust_reg_min_max_vals(struct bpf_verifier_env *env,
* an arbitrary scalar. Disallow all math except
* pointer subtraction
*/
- if (opcode == BPF_SUB){
+ if (opcode == BPF_SUB && env->allow_ptr_leaks) {
mark_reg_unknown(env, regs, insn->dst_reg);
return 0;
}
--
2.17.1
next reply other threads:[~2018-09-13 2:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-12 21:06 Alexei Starovoitov [this message]
2018-09-12 21:48 ` [PATCH bpf] bpf/verifier: disallow pointer subtraction Daniel Borkmann
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