On 7/28/22 10:49 PM, Zeng Jingxiang wrote:
From: Zeng Jingxiang <linuszeng@xxxxxxxxxxx> 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@xxxxxxxxxxx> --- 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)
