blobmsg: fix missing length checks

blobmsg_check_attr_len was calling blobmsg_check_data for some, but not all
attribute types. These checks was missing for arrays and tables.

Additionally, the length check in blobmsg_check_data was a bit off, since
it was comparing the blobmsg data length against the raw blob attr length.

Fix this by checking the raw blob length against the buffer length in
blobmsg_hdr_from_blob

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/blobmsg.c b/blobmsg.c
index 308bef7bc6b052bf708308b6789e96b514c88bbb..7da41838029984bd94b367ceb320b016aaa9fd9c 100644 (file)
--- a/blobmsg.c
+++ b/blobmsg.c
@@ -30,31 +30,18 @@ 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)
+static bool blobmsg_check_name(const struct blob_attr *attr, bool name)
 {
        const struct blobmsg_hdr *hdr;
        uint16_t namelen;
 
-       hdr = blobmsg_hdr_from_blob(attr, len);
-       if (!hdr)
+       if (!blob_is_extended(attr))
+               return !name;
+
+       if (blob_len(attr) < sizeof(struct blobmsg_hdr))
                return false;
 
+       hdr = (const struct blobmsg_hdr *)blob_data(attr);
        if (name && !hdr->namelen)
                return false;
 
@@ -68,29 +55,20 @@ static bool blobmsg_check_name(const struct blob_attr *attr, size_t len, bool na
        return true;
 }
 
-static const char* blobmsg_check_data(const struct blob_attr *attr, size_t len, size_t *data_len)
-{
-       char *limit = (char *) attr + len;
-       const char *data;
-
-       *data_len = blobmsg_data_len(attr);
-       if (*data_len > blob_raw_len(attr))
-               return NULL;
-
-       data = blobmsg_data(attr);
-       if (data + *data_len > limit)
-               return NULL;
-
-       return data;
-}
-
 bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len)
 {
        const char *data;
        size_t data_len;
        int id;
 
-       if (!blobmsg_check_name(attr, len, name))
+       if (len < sizeof(struct blob_attr))
+               return false;
+
+       data_len = blob_raw_len(attr);
+       if (data_len < sizeof(struct blob_attr) || data_len > len)
+               return false;
+
+       if (!blobmsg_check_name(attr, name))
                return false;
 
        id = blob_id(attr);
@@ -100,9 +78,8 @@ bool blobmsg_check_attr_len(const struct blob_attr *attr, bool name, size_t len)
        if (!blob_type[id])
                return true;
 
-       data = blobmsg_check_data(attr, len, &data_len);
-       if (!data)
-               return false;
+       data = blobmsg_data(attr);
+       data_len = blobmsg_data_len(attr);
 
        return blob_check_type(data, data_len, blob_type[id]);
 }
@@ -206,13 +183,13 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
        }
 
        __blob_for_each_attr(attr, data, len) {
-               hdr = blobmsg_hdr_from_blob(attr, len);
-               if (!hdr)
+               if (!blobmsg_check_attr_len(attr, false, len))
                        return -1;
 
-               if (!blobmsg_hdr_valid_namelen(hdr, len))
-                       return -1;
+               if (!blob_is_extended(attr))
+                       continue;
 
+               hdr = blob_data(attr);
                for (i = 0; i < policy_len; i++) {
                        if (!policy[i].name)
                                continue;
@@ -224,9 +201,6 @@ int blobmsg_parse(const struct blobmsg_policy *policy, int policy_len,
                        if (blobmsg_namelen(hdr) != pslen[i])
                                continue;
 
-                       if (!blobmsg_check_attr_len(attr, true, len))
-                               return -1;
-
                        if (tb[i])
                                continue;