[PATCH 4.9 73/78] USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb()

Greg Kroah-Hartman
2020-09-01T17:10:30Z

From: Brooke Basile <brookebasile@gmail.com>

commit 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 upstream.

Some values extracted by ncm_unwrap_ntb() could possibly lead to several
different out of bounds reads of memory. Specifically the values passed
to netdev_alloc_skb_ip_align() need to be checked so that memory is not
overflowed.

Resolve this by applying bounds checking to a number of different
indexes and lengths of the structure parsing logic.

Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Brooke Basile <brookebasile@gmail.com>
Acked-by: Felipe Balbi <balbi@kernel.org>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/gadget/function/f_ncm.c | 81 ++++++++++++++++++++++++++++++------
1 file changed, 69 insertions(+), 12 deletions(-)

--- a/drivers/usb/gadget/function/f_ncm.c
+++ b/drivers/usb/gadget/function/f_ncm.c
@@ -1209,12 +1209,15 @@ static int ncm_unwrap_ntb(struct gether
int ndp_index;
unsigned dg_len, dg_len2;
unsigned ndp_len;
+ unsigned block_len;
struct sk_buff *skb2;
int ret = -EINVAL;
- unsigned max_size = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
+ unsigned ntb_max = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize);
+ unsigned frame_max = le16_to_cpu(ecm_desc.wMaxSegmentSize);
const struct ndp_parser_opts *opts = ncm->parser_opts;
unsigned crc_len = ncm->is_crc ? sizeof(uint32_t) : 0;
int dgram_counter;
+ bool ndp_after_header;

/* dwSignature */
if (get_unaligned_le32(tmp) != opts->nth_sign) {
@@ -1233,25 +1236,37 @@ static int ncm_unwrap_ntb(struct gether
}
tmp++; /* skip wSequence */

+ block_len = get_ncm(&tmp, opts->block_length);
/* (d)wBlockLength */
- if (get_ncm(&tmp, opts->block_length) > max_size) {
+ if (block_len > ntb_max) {
INFO(port->func.config->cdev, "OUT size exceeded\n");
goto err;
}

ndp_index = get_ncm(&tmp, opts->ndp_index);
+ ndp_after_header = false;

/* Run through all the NDP's in the NTB */
do {
- /* NCM 3.2 */
- if (((ndp_index % 4) != 0) &&
- (ndp_index < opts->nth_size)) {
+ /*
+ * NCM 3.2
+ * dwNdpIndex
+ */
+ if (((ndp_index % 4) != 0) ||
+ (ndp_index < opts->nth_size) ||
+ (ndp_index > (block_len -
+ opts->ndp_size))) {
INFO(port->func.config->cdev, "Bad index: %#X\n",
ndp_index);
goto err;
}
+ if (ndp_index == opts->nth_size)
+ ndp_after_header = true;

- /* walk through NDP */
+ /*
+ * walk through NDP
+ * dwSignature
+ */
tmp = (void *)(skb->data + ndp_index);
if (get_unaligned_le32(tmp) != ncm->ndp_sign) {
INFO(port->func.config->cdev, "Wrong NDP SIGN\n");
@@ -1262,14 +1277,15 @@ static int ncm_unwrap_ntb(struct gether
ndp_len = get_unaligned_le16(tmp++);
/*
* NCM 3.3.1
+ * wLength
* entry is 2 items
* item size is 16/32 bits, opts->dgram_item_len * 2 bytes
* minimal: struct usb_cdc_ncm_ndpX + normal entry + zero entry
* Each entry is a dgram index and a dgram length.
*/
if ((ndp_len < opts->ndp_size
- + 2 * 2 * (opts->dgram_item_len * 2))
- || (ndp_len % opts->ndplen_align != 0)) {
+ + 2 * 2 * (opts->dgram_item_len * 2)) ||
+ (ndp_len % opts->ndplen_align != 0)) {
INFO(port->func.config->cdev, "Bad NDP length: %#X\n",
ndp_len);
goto err;
@@ -1286,8 +1302,21 @@ static int ncm_unwrap_ntb(struct gether

do {
index = index2;
+ /* wDatagramIndex[0] */
+ if ((index < opts->nth_size) ||
+ (index > block_len - opts->dpe_size)) {
+ INFO(port->func.config->cdev,
+ "Bad index: %#X\n", index);
+ goto err;
+ }
+
dg_len = dg_len2;
- if (dg_len < 14 + crc_len) { /* ethernet hdr + crc */
+ /*
+ * wDatagramLength[0]
+ * ethernet hdr + crc or larger than max frame size
+ */
+ if ((dg_len < 14 + crc_len) ||
+ (dg_len > frame_max)) {
INFO(port->func.config->cdev,
"Bad dgram length: %#X\n", dg_len);
goto err;
@@ -1311,6 +1340,37 @@ static int ncm_unwrap_ntb(struct gether
index2 = get_ncm(&tmp, opts->dgram_item_len);
dg_len2 = get_ncm(&tmp, opts->dgram_item_len);

+ if (index2 == 0 || dg_len2 == 0)
+ break;
+
+ /* wDatagramIndex[1] */
+ if (ndp_after_header) {
+ if (index2 < opts->nth_size + opts->ndp_size) {
+ INFO(port->func.config->cdev,
+ "Bad index: %#X\n", index2);
+ goto err;
+ }
+ } else {
+ if (index2 < opts->nth_size + opts->dpe_size) {
+ INFO(port->func.config->cdev,
+ "Bad index: %#X\n", index2);
+ goto err;
+ }
+ }
+ if (index2 > block_len - opts->dpe_size) {
+ INFO(port->func.config->cdev,
+ "Bad index: %#X\n", index2);
+ goto err;
+ }
+
+ /* wDatagramLength[1] */
+ if ((dg_len2 < 14 + crc_len) ||
+ (dg_len2 > frame_max)) {
+ INFO(port->func.config->cdev,
+ "Bad dgram length: %#X\n", dg_len);
+ goto err;
+ }
+
/*
* Copy the data into a new skb.
* This ensures the truesize is correct
@@ -1327,9 +1387,6 @@ static int ncm_unwrap_ntb(struct gether
ndp_len -= 2 * (opts->dgram_item_len * 2);

dgram_counter++;
-
- if (index2 == 0 || dg_len2 == 0)
- break;
} while (ndp_len > 2 * (opts->dgram_item_len * 2));
} while (ndp_index);