From: Alexei Starovoitov <ast@kernel.org>
Date: Wed, 12 Sep 2018 14:06:10 -0700
Subject: bpf/verifier: disallow pointer subtraction
Patch-mainline: v4.19-rc5
Git-commit: dd066823db2ac4e22f721ec85190817b58059a54
References: bsc#1083647
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>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Gary Lin <glin@suse.com>
---
kernel/bpf/verifier.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2311,7 +2311,7 @@ static int adjust_reg_min_max_vals(struc
* 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;
}