releases/4.9.72/bpf-adjust-insn_aux_data-when-patching-insns.patch

From foo@baz Fri Dec 22 16:57:35 CET 2017
From: Daniel Borkmann <daniel@iogearbox.net>
Date: Fri, 22 Dec 2017 16:29:02 +0100
Subject: bpf: adjust insn_aux_data when patching insns
To: gregkh@linuxfoundation.org
Cc: ast@kernel.org, daniel@iogearbox.net, jannh@google.com, stable@vger.kernel.org, Alexei Starovoitov <ast@fb.com>, "David S . Miller" <davem@davemloft.net>
Message-ID: <20171222152905.3455-2-daniel@iogearbox.net>

From: Daniel Borkmann <daniel@iogearbox.net>


From: Alexei Starovoitov <ast@fb.com>

[ Upstream commit 8041902dae5299c1f194ba42d14383f734631009 ]

convert_ctx_accesses() replaces single bpf instruction with a set of
instructions. Adjust corresponding insn_aux_data while patching.
It's needed to make sure subsequent 'for(all insn)' loops
have matching insn and insn_aux_data.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/bpf/verifier.c |   44 +++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 39 insertions(+), 5 deletions(-)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -3210,6 +3210,41 @@ static void convert_pseudo_ld_imm64(stru
 			insn->src_reg = 0;
 }
 
+/* single env->prog->insni[off] instruction was replaced with the range
+ * insni[off, off + cnt).  Adjust corresponding insn_aux_data by copying
+ * [0, off) and [off, end) to new locations, so the patched range stays zero
+ */
+static int adjust_insn_aux_data(struct bpf_verifier_env *env, u32 prog_len,
+				u32 off, u32 cnt)
+{
+	struct bpf_insn_aux_data *new_data, *old_data = env->insn_aux_data;
+
+	if (cnt == 1)
+		return 0;
+	new_data = vzalloc(sizeof(struct bpf_insn_aux_data) * prog_len);
+	if (!new_data)
+		return -ENOMEM;
+	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));
+	env->insn_aux_data = new_data;
+	vfree(old_data);
+	return 0;
+}
+
+static struct bpf_prog *bpf_patch_insn_data(struct bpf_verifier_env *env, u32 off,
+					    const struct bpf_insn *patch, u32 len)
+{
+	struct bpf_prog *new_prog;
+
+	new_prog = bpf_patch_insn_single(env->prog, off, patch, len);
+	if (!new_prog)
+		return NULL;
+	if (adjust_insn_aux_data(env, new_prog->len, off, len))
+		return NULL;
+	return new_prog;
+}
+
 /* convert load instructions that access fields of 'struct __sk_buff'
  * into sequence of instructions that access fields of 'struct sk_buff'
  */
@@ -3229,10 +3264,10 @@ static int convert_ctx_accesses(struct b
 			verbose("bpf verifier is misconfigured\n");
 			return -EINVAL;
 		} else if (cnt) {
-			new_prog = bpf_patch_insn_single(env->prog, 0,
-							 insn_buf, cnt);
+			new_prog = bpf_patch_insn_data(env, 0, insn_buf, cnt);
 			if (!new_prog)
 				return -ENOMEM;
+
 			env->prog = new_prog;
 			delta += cnt - 1;
 		}
@@ -3253,7 +3288,7 @@ static int convert_ctx_accesses(struct b
 		else
 			continue;
 
-		if (env->insn_aux_data[i].ptr_type != PTR_TO_CTX)
+		if (env->insn_aux_data[i + delta].ptr_type != PTR_TO_CTX)
 			continue;
 
 		cnt = ops->convert_ctx_access(type, insn->dst_reg, insn->src_reg,
@@ -3263,8 +3298,7 @@ static int convert_ctx_accesses(struct b
 			return -EINVAL;
 		}
 
-		new_prog = bpf_patch_insn_single(env->prog, i + delta, insn_buf,
-						 cnt);
+		new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, cnt);
 		if (!new_prog)
 			return -ENOMEM;