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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: 849fa50662 ("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
This commit is contained in:
John Fastabend 2020-03-30 14:36:59 -07:00 committed by Alexei Starovoitov
parent 3f50f132d8
commit fa123ac022
1 changed files with 1 additions and 0 deletions
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kernel/bpf/verifier.c
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@ -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);