blobmsg: blobmsg_parse and blobmsg_parse_array oob read fixes

[oweals/libubox.git] / blobmsg.c

diff --git a/blobmsg.c b/blobmsg.c
index 3e34821cc9284c64c9f220ab2b2de66b4c42a4a1..762078436f9bba18c5b105831d5db2a69b50e7a5 100644 (file)
--- a/blobmsg.c
+++ b/blobmsg.c
@@ -30,16 +30,38 @@ bool blobmsg_check_attr(const struct blob_attr *attr, bool name)
        return blobmsg_check_attr_len(attr, name, blob_raw_len(attr));
 }
 
+static const struct blobmsg_hdr* blobmsg_hdr_from_blob(const struct blob_attr *attr, size_t len)
+{
+       if (len < sizeof(struct blob_attr) + sizeof(struct blobmsg_hdr))
+               return NULL;
+
+       return blob_data(attr);
+}
+
+static bool blobmsg_hdr_valid_namelen(const struct blobmsg_hdr *hdr, size_t len)
+{
+       if (len < sizeof(struct blob_attr) + sizeof(struct blobmsg_hdr) + blobmsg_namelen(hdr) + 1)
+               return false;
+
+       return true;
+}
+
 static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool name)
 {
        char *limit = (char *) attr + len;
        const struct blobmsg_hdr *hdr;
 
-       hdr = blob_data(attr);
+       hdr = blobmsg_hdr_from_blob(attr, len);
+       if (!hdr)
+               return false;
+
        if (name && !hdr->namelen)
                return false;
 
-       if ((char *) hdr->name + blobmsg_namelen(hdr) > limit)
+       if (name && !blobmsg_hdr_valid_namelen(hdr, len))
+               return false;
+
+       if ((char *) hdr->name + blobmsg_namelen(hdr) + 1 > limit)
                return false;
 
        if (blobmsg_namelen(hdr) > (blob_len(attr) - sizeof(struct blobmsg_hdr)))
@@ -73,9 +95,6 @@ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len)
        size_t data_len;
        int id;
 
-       if (len < sizeof(struct blob_attr))
-               return false;
-
        if (!blobmsg_check_name(attr, len, name))
                return false;
 
@@ -170,11 +189,10 @@ int blobmsg_parse_array(const struct blobmsg_policy *policy, int policy_len,
        return 0;
 }
 
-
 int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
                   struct blob_attr **tb, void *data, unsigned int len)
 {
-       struct blobmsg_hdr *hdr;
+       const struct blobmsg_hdr *hdr;
        struct blob_attr *attr;
        uint8_t *pslen;
        int i;
@@ -191,7 +209,13 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
        }
 
        __blob_for_each_attr(attr, data, len) {
-               hdr = blob_data(attr);
+               hdr = blobmsg_hdr_from_blob(attr, len);
+               if (!hdr)
+                       return -1;
+
+               if (!blobmsg_hdr_valid_namelen(hdr, len))
+                       return -1;
+
                for (i = 0; i < policy_len; i++) {
                        if (!policy[i].name)
                                continue;