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authorAlexei Starovoitov <ast@kernel.org>2018-09-12 14:06:10 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2018-09-12 23:30:02 +0200
commitdd066823db2ac4e22f721ec85190817b58059a54 (patch)
treef7f40317bb1474a382035fb58a120e73c82fec46 /kernel
parent4b1c5d917d34f705096bb7dd8a2bd19b0881970e (diff)
downloadlinux-stericsson-dd066823db2ac4e22f721ec85190817b58059a54.tar.gz
bpf/verifier: disallow pointer subtraction
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>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/verifier.c2
1 files changed, 1 insertions, 1 deletions
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;
}