DGNum/libubox
6
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

blobmsg: fix missing length checks

Browse source 
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>
This commit is contained in:
Felix Fietkau 2020-05-25 12:40:04 +02:00
parent 639c29d197
commit 66195aee50
1 changed files with 20 additions and 46 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

66
blobmsg.c
View file

@ -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;