From b9979db8340154526d9ab38a1883d6f6ba9b6d47 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 1 Nov 2021 15:21:51 -0700 Subject: bpf: Fix propagation of bounds from 64-bit min/max into 32-bit and var_off. Before this fix: 166: (b5) if r2 <= 0x1 goto pc+22 from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff)) After this fix: 166: (b5) if r2 <= 0x1 goto pc+22 from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1)) While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1 and call __reg_combine_64_into_32(true_reg). Without the fix it would not pass the condition: if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value)) since umin_value == 0 at this point. Before commit 10bf4e83167c the umin was incorrectly ingored. The commit 10bf4e83167c fixed the correctness issue, but pessimized propagation of 64-bit min max into 32-bit min max and corresponding var_off. Fixes: 10bf4e83167c ("bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds") Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20211101222153.78759-1-alexei.starovoitov@gmail.com --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 3c8aa7df1773..29671ed49ee8 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1425,7 +1425,7 @@ static bool __reg64_bound_s32(s64 a) static bool __reg64_bound_u32(u64 a) { - return a > U32_MIN && a < U32_MAX; + return a >= U32_MIN && a <= U32_MAX; } static void __reg_combine_64_into_32(struct bpf_reg_state *reg) -- cgit v1.2.3