Revert "bpf: fix branch pruning logic"

This reverts commit 1367d854b97493bfb1f3d24cf89ba60cb7f059ea.

Signed-off-by: Chatur27 <jasonbright2709@gmail.com>

1 files changed, 0 insertions, 28 deletions

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index a62679711de0..014c2d759916 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -191,7 +191,6 @@ struct bpf_insn_aux_data {
 		enum bpf_reg_type ptr_type;	/* pointer type for load/store insns */
 		struct bpf_map *map_ptr;	/* pointer for call insn into lookup_elem */
 	};
-	bool seen; /* this insn was processed by the verifier */
 };
 
 #define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
@@ -1794,7 +1793,6 @@ static int do_check(struct verifier_env *env)
 			print_bpf_insn(env, insn);
 		}
 
-		env->insn_aux_data[insn_idx].seen = true;
 		if (class == BPF_ALU || class == BPF_ALU64) {
 			err = check_alu_op(env, insn);
 			if (err)
@@ -1990,7 +1988,6 @@ process_bpf_exit:
 					return err;
 
 				insn_idx++;
-				env->insn_aux_data[insn_idx].seen = true;
 			} else {
 				verbose("invalid BPF_LD mode\n");
 				return -EINVAL;
@@ -2128,7 +2125,6 @@ static int adjust_insn_aux_data(struct verifier_env *env, u32 prog_len,
 				u32 off, u32 cnt)
 {
 	struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
-	int i;
 
 	if (cnt == 1)
 		return 0;
@@ -2138,8 +2134,6 @@ static int adjust_insn_aux_data(struct verifier_env *env, u32 prog_len,
 	memcpy(new_data, old_data, sizeof(struct bpf_insn_aux_data) * off);
 	memcpy(new_data + off + cnt - 1, old_data + off,
 	       sizeof(struct bpf_insn_aux_data) * (prog_len - off - cnt + 1));
-	for (i = off; i < off + cnt - 1; i++)
-		new_data[i].seen = true;
 	env->insn_aux_data = new_data;
 	vfree(old_data);
 	return 0;
@@ -2158,25 +2152,6 @@ static struct bpf_prog *bpf_patch_insn_data(struct verifier_env *env, u32 off,
 	return new_prog;
 }
 
-/* The verifier does more data flow analysis than llvm and will not explore
- * branches that are dead at run time. Malicious programs can have dead code
- * too. Therefore replace all dead at-run-time code with nops.
- */
-static void sanitize_dead_code(struct verifier_env *env)
-{
-	struct bpf_insn_aux_data *aux_data = env->insn_aux_data;
-	struct bpf_insn nop = BPF_MOV64_REG(BPF_REG_0, BPF_REG_0);
-	struct bpf_insn *insn = env->prog->insnsi;
-	const int insn_cnt = env->prog->len;
-	int i;
-
-	for (i = 0; i < insn_cnt; i++) {
-		if (aux_data[i].seen)
-			continue;
-		memcpy(insn + i, &nop, sizeof(nop));
-	}
-}
-
 /* convert load instructions that access fields of 'struct __sk_buff'
  * into sequence of instructions that access fields of 'struct sk_buff'
  */
@@ -2396,9 +2371,6 @@ skip_full_check:
 	free_states(env);
 
 	if (ret == 0)
-		sanitize_dead_code(env);
-
-	if (ret == 0)
 		/* program is valid, convert *(u32*)(ctx + off) accesses */
 		ret = convert_ctx_accesses(env);