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authorJiri Slaby <jslaby@suse.cz>2018-01-12 14:59:55 +0100
committerJiri Slaby <jslaby@suse.cz>2018-01-12 16:49:36 +0100
commit09e37ea04262ba328ea30d6744ac0090b4c87778 (patch)
treebbe87ccf0d44abdae66f16230e7e3b525fd7b530
parentabc259adb8a9331bfac27070a57123c6383cdad3 (diff)
bpf: adjust insn_aux_data when patching insns (bsc#1068032
CVE-2017-5753). suse-commit: 74eccd861f237a3b1414d43f95ae4ee8db189e13
-rw-r--r--kernel/bpf/verifier.c40
1 files changed, 37 insertions, 3 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 47bb3eee950c..bb4b5405d1a5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2107,6 +2107,41 @@ static void convert_pseudo_ld_imm64(struct verifier_env *env)
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 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 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'
*/
@@ -2132,7 +2167,7 @@ static int convert_ctx_accesses(struct verifier_env *env)
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 = env->prog->aux->ops->
@@ -2143,8 +2178,7 @@ static int convert_ctx_accesses(struct verifier_env *env)
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;