Messages in this thread | | | Date | Fri, 29 Jul 2022 10:15:21 -0700 | Subject | Re: [PATCH] bpf/verifier: fix control flow issues in __reg64_bound_u32() | From | Yonghong Song <> |
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On 7/28/22 10:49 PM, Zeng Jingxiang wrote: > From: Zeng Jingxiang <linuszeng@tencent.com> > > This greater-than-or-equal-to-zero comparison of an unsigned value > is always true. "a >= U32_MIN". > 1632 return a >= U32_MIN && a <= U32_MAX; > > Fixes: b9979db83401 ("bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off.") > Signed-off-by: Zeng Jingxiang <linuszeng@tencent.com> > --- > kernel/bpf/verifier.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 0efbac0fd126..dd67108fb1d7 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -1629,7 +1629,7 @@ static bool __reg64_bound_s32(s64 a) > > static bool __reg64_bound_u32(u64 a) > { > - return a >= U32_MIN && a <= U32_MAX; > + return a <= U32_MAX; > }
I cannot find the related link. But IIRC, Alexei commented that the code is written this way to express the intention (within 32bit bounds) so this patch is unnecessary...
> > static void __reg_combine_64_into_32(struct bpf_reg_state *reg)
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