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bpf/verifier: disallow pointer subtraction 

Subtraction of pointers was accidentally allowed for unpriv programs
by commit 82abbf8d2f. Revert that part of commit.

Fixes: 82abbf8d2f ("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>
This commit is contained in:
Alexei Starovoitov 2018-09-12 14:06:10 -07:00 committed by Daniel Borkmann
parent 4b1c5d917d
commit dd066823db
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/verifier.c
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@ -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;
}