Commit ea25f914 authored Dec 18, 2017 by Jann Horn Committed by Daniel Borkmann Dec 21, 2017

bpf: fix missing error return in check_stack_boundary()



Prevent indirect stack accesses at non-constant addresses, which would
permit reading and corrupting spilled pointers.

Fixes: f1174f77 ("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>

parent 468f6eaf

kernel/bpf/verifier.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -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 \|\|