From: Alexei Starovoitov <ast@xxxxxxxxxx>
commit dd066823db2ac4e22f721ec85190817b58059a54 upstream.
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@xxxxxxxxxx>
Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
[fllinden@xxxxxxxxxx: backport to 4.14]
Signed-off-by: Frank van der Linden <fllinden@xxxxxxxxxx>
---
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 b999e268ee23..5c440398e0a1 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2754,7 +2754,7 @@ 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(regs, insn->dst_reg);
return 0;
}
--
2.23.4
