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From 5e75160f48785464f9213c6bc8c72b9372c5318b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
Date: Sat, 23 May 2020 13:18:51 +0200
Subject: [PATCH] blobmsg: fix attrs iteration in the blobmsg_check_array_len()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Starting with 75e300aeec25 ("blobmsg: fix wrong payload len passed from
blobmsg_check_array") blobmsg_check_array_len() gets *blob* length
passed as argument. It cannot be used with __blobmsg_for_each_attr()
which expects *data* length.
Use blobmsg_for_each_attr() which calculates *data* length on its own.
The same bug was already reported in the past and there was fix attempt
in the commit cd75136b1342 ("blobmsg: fix wrong payload len passed from
blobmsg_check_array"). That change made blobmsg_check_attr_len() calls
fail however.
This is hopefully the correct & complete fix:
1. blobmsg_check_array_len() gets *blob* length
2. It calls blobmsg_check_attr_len() which requires *blob* length
3. It uses blobmsg_for_each_attr() which gets *data* length
This fixes iterating over random memory treated as attrs. That was
resulting in check failing randomly for totally correct blobs. It's
critical e.g. for procd project with its instance_fill_array() failing
and procd not starting services.
Fixes: 75e300aeec25 ("blobmsg: fix wrong payload len passed from blobmsg_check_array")
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
---
blobmsg.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/blobmsg.c
+++ b/blobmsg.c
@@ -123,16 +123,18 @@ int blobmsg_check_array(const struct blo
return blobmsg_check_array_len(attr, type, blob_len(attr));
}
-int blobmsg_check_array_len(const struct blob_attr *attr, int type, size_t len)
+int blobmsg_check_array_len(const struct blob_attr *attr, int type,
+ size_t blob_len)
{
struct blob_attr *cur;
+ size_t rem;
bool name;
int size = 0;
if (type > BLOBMSG_TYPE_LAST)
return -1;
- if (!blobmsg_check_attr_len(attr, false, len))
+ if (!blobmsg_check_attr_len(attr, false, blob_len))
return -1;
switch (blobmsg_type(attr)) {
@@ -146,11 +148,11 @@ int blobmsg_check_array_len(const struct
return -1;
}
- __blobmsg_for_each_attr(cur, attr, len) {
+ blobmsg_for_each_attr(cur, attr, rem) {
if (type != BLOBMSG_TYPE_UNSPEC && blobmsg_type(cur) != type)
return -1;
- if (!blobmsg_check_attr_len(cur, name, len))
+ if (!blobmsg_check_attr_len(cur, name, rem))
return -1;
size++;
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