From fa123ac022e425becce11f1a6c7ee4d283f75a90 Mon Sep 17 00:00:00 2001
From: John Fastabend <john.fastabend@gmail.com>
Date: Mon, 30 Mar 2020 14:36:59 -0700
Subject: [PATCH] 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: 849fa50662fbc ("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
---
kernel/bpf/verifier.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 1c60d001bb462..04c6630cc18f9 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -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);
--
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