Re: [PATCH v2 bpf-next 2/3] bpf: Fix propagation of signed bounds from 64-bit min/max into 32-bit.
From: Yonghong Song <hidden>
Date: 2021-11-01 23:03:57
Also in:
bpf
On 11/1/21 3:21 PM, Alexei Starovoitov wrote:
From: Alexei Starovoitov <ast@kernel.org>
Similar to unsigned bounds propagation fix signed bounds.
The 'Fixes' tag is a hint. There is no security bug here.
The verifier was too conservative.
Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>The change looks good. Should a new test_verifier test be added to exercise the new change?
quoted hunk ↗ jump to hunk
--- 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 29671ed49ee8..a4b48bd4e3ca 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c@@ -1420,7 +1420,7 @@ static void __reg_combine_32_into_64(struct bpf_reg_state *reg) static bool __reg64_bound_s32(s64 a) { - return a > S32_MIN && a < S32_MAX; + return a >= S32_MIN && a <= S32_MAX; } static bool __reg64_bound_u32(u64 a)