Commit fa123ac0 authored Mar 30, 2020 by John Fastabend Committed by Alexei Starovoitov Mar 30, 2020

bpf: Verifier, refine 32bit bound in do_refine_retval_range

Further refine return values range in do_refine_retval_range by noting
these are int return types (We will assume here that int is a 32-bit type).

Two reasons to pull this out of original patch. First it makes the original
fix impossible to backport. And second I've not seen this as being problematic
in practice unlike the other case.

Fixes: 849fa506 ("bpf/verifier: refine retval R0 state for bpf_get_stack helper")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/158560421952.10843.12496354931526965046.stgit@john-Precision-5820-Tower

parent 3f50f132

kernel/bpf/verifier.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -4335,6 +4335,7 @@ static void do_refine_retval_range(struct bpf_reg_state *regs, int ret_type,
		return;

		ret_reg->smax_value = meta->msize_max_value;
		ret_reg->s32_max_value = meta->msize_max_value;
		__reg_deduce_bounds(ret_reg);
		__reg_bound_offset(ret_reg);
		__update_reg_bounds(ret_reg);