From: Jann Horn jannh@google.com
[ Upstream commit 179d1c5602997fef5a940c6ddcf31212cbfebd14 ]
This could be made safe by passing through a reference to env and checking for env->allow_ptr_leaks, but it would only work one way and is probably not worth the hassle - not doing it will not directly lead to program rejection.
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 | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 8c35355..5a30eda 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3337,15 +3337,14 @@ static bool regsafe(struct bpf_reg_state *rold, struct bpf_reg_state *rcur, return range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off); } else { - /* if we knew anything about the old value, we're not - * equal, because we can't know anything about the - * scalar value of the pointer in the new value. + /* We're trying to use a pointer in place of a scalar. + * Even if the scalar was unbounded, this could lead to + * pointer leaks because scalars are allowed to leak + * while pointers are not. We could make this safe in + * special cases if root is calling us, but it's + * probably not worth the hassle. */ - return rold->umin_value == 0 && - rold->umax_value == U64_MAX && - rold->smin_value == S64_MIN && - rold->smax_value == S64_MAX && - tnum_is_unknown(rold->var_off); + return false; } case PTR_TO_MAP_VALUE: /* If the new min/max/var_off satisfy the old ones and