bpf: fix missing error return in check_stack_boundary()
authorJann Horn <jannh@google.com>
Tue, 19 Dec 2017 04:11:57 +0000 (20:11 -0800)
committerDaniel Borkmann <daniel@iogearbox.net>
Thu, 21 Dec 2017 01:15:41 +0000 (02:15 +0100)
Prevent indirect stack accesses at non-constant addresses, which would
permit reading and corrupting spilled pointers.

Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
kernel/bpf/verifier.c

index ecdc265244ca1df6bad7d390717ea387aa8c0b04..77e4b5223867a2f5ca6f49454ab16cb7e3f22df2 100644 (file)
@@ -1303,6 +1303,7 @@ static int check_stack_boundary(struct bpf_verifier_env *env, int regno,
                tnum_strn(tn_buf, sizeof(tn_buf), regs[regno].var_off);
                verbose(env, "invalid variable stack read R%d var_off=%s\n",
                        regno, tn_buf);
+               return -EACCES;
        }
        off = regs[regno].off + regs[regno].var_off.value;
        if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||