From: Yonghong Song <yhs@fb.com>
Date: Sat, 28 Apr 2018 22:28:10 -0700
Subject: bpf: remove never-hit branches in verifier adjust_scalar_min_max_vals
Patch-mainline: v4.18-rc1
Git-commit: afbe1a5b79cd18f0ace9107e6b4cd7aa193e5e52
References: bsc#1109837
In verifier function adjust_scalar_min_max_vals,
when src_known is false and the opcode is BPF_LSH/BPF_RSH,
early return will happen in the function. So remove
the branch in handling BPF_LSH/BPF_RSH when src_known is false.
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
kernel/bpf/verifier.c | 11 ++---------
1 file changed, 2 insertions(+), 9 deletions(-)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2954,10 +2954,7 @@ static int adjust_scalar_min_max_vals(st
dst_reg->umin_value <<= umin_val;
dst_reg->umax_value <<= umax_val;
}
- if (src_known)
- dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
- else
- dst_reg->var_off = tnum_lshift(tnum_unknown, umin_val);
+ dst_reg->var_off = tnum_lshift(dst_reg->var_off, umin_val);
/* We may learn something more from the var_off */
__update_reg_bounds(dst_reg);
break;
@@ -2985,11 +2982,7 @@ static int adjust_scalar_min_max_vals(st
*/
dst_reg->smin_value = S64_MIN;
dst_reg->smax_value = S64_MAX;
- if (src_known)
- dst_reg->var_off = tnum_rshift(dst_reg->var_off,
- umin_val);
- else
- dst_reg->var_off = tnum_rshift(tnum_unknown, umin_val);
+ dst_reg->var_off = tnum_rshift(dst_reg->var_off, umin_val);
dst_reg->umin_value >>= umax_val;
dst_reg->umax_value >>= umin_val;
/* We may learn something more from the var_off */