Re: [PATCH] bpf: clean up unnecessary conditional judgments
From: Yonghong Song <hidden>
Date: 2021-12-22 16:05:10
On 12/22/21 5:10 AM, Jackie Liu wrote:
quoted hunk ↗ jump to hunk
From: Jackie Liu <redacted> s32 is always true regardless of the values of its operands. let's cleanup. Fixes: e572ff80f05c ("bpf: Make 32->64 bounds propagation slightly more robust") Reported-by: k2ci <redacted> Signed-off-by: Jackie Liu <redacted> --- kernel/bpf/verifier.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b532f1058d35..43812ee58304 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c@@ -1366,11 +1366,6 @@ static void __reg_bound_offset(struct bpf_reg_state *reg) reg->var_off = tnum_or(tnum_clear_subreg(var64_off), var32_off); } -static bool __reg32_bound_s64(s32 a) -{ - return a >= 0 && a <= S32_MAX; -}
The following bpf tree commit triggered the above change:
commit e572ff80f05c33cd0cb4860f864f5c9c044280b6
Author: Daniel Borkmann [off-list ref]
Date: Wed Dec 15 22:28:48 2021 +0000
bpf: Make 32->64 bounds propagation slightly more robust
There is no need to fix bpf tree since as this patch just a cleanup
patch and there is no functionality change.
Maybe wait for the above patch available in bpf-next and submit
this patch again? Daniel, do you have any suggestions for this patch?
quoted hunk ↗ jump to hunk
- static void __reg_assign_32_into_64(struct bpf_reg_state *reg) { reg->umin_value = reg->u32_min_value;@@ -1380,8 +1375,7 @@ static void __reg_assign_32_into_64(struct bpf_reg_state *reg) * be positive otherwise set to worse case bounds and refine later * from tnum. */ - if (__reg32_bound_s64(reg->s32_min_value) && - __reg32_bound_s64(reg->s32_max_value)) { + if (reg->s32_min_value >= 0 && reg->s32_max_value >= 0) { reg->smin_value = reg->s32_min_value; reg->smax_value = reg->s32_max_value; } else {