From: Bryan O'Donoghue bryan.odonoghue@linaro.org
commit 2b405533c2560d7878199c57d95a39151351df72 upstream.
commit 2b74b0a04d3e ("USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb()") adds important bounds checking however it unfortunately also introduces a bug with respect to section 3.3.1 of the NCM specification.
wDatagramIndex[1] : "Byte index, in little endian, of the second datagram described by this NDP16. If zero, then this marks the end of the sequence of datagrams in this NDP16."
wDatagramLength[1]: "Byte length, in little endian, of the second datagram described by this NDP16. If zero, then this marks the end of the sequence of datagrams in this NDP16."
wDatagramIndex[1] and wDatagramLength[1] respectively then may be zero but that does not mean we should throw away the data referenced by wDatagramIndex[0] and wDatagramLength[0] as is currently the case.
Breaking the loop on (index2 == 0 || dg_len2 == 0) should come at the end as was previously the case and checks for index2 and dg_len2 should be removed since zero is valid.
I'm not sure how much testing the above patch received but for me right now after enumeration ping doesn't work. Reverting the commit restores ping, scp, etc.
The extra validation associated with wDatagramIndex[0] and wDatagramLength[0] appears to be valid so, this change removes the incorrect restriction on wDatagramIndex[1] and wDatagramLength[1] restoring data processing between host and device.
Fixes: 2b74b0a04d3e ("USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb()") Cc: Ilja Van Sprundel ivansprundel@ioactive.com Cc: Brooke Basile brookebasile@gmail.com Cc: stable stable@kernel.org Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org Link: https://lore.kernel.org/r/20200920170158.1217068-1-bryan.odonoghue@linaro.or... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/usb/gadget/function/f_ncm.c | 30 ++---------------------------- 1 file changed, 2 insertions(+), 28 deletions(-)
--- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1217,7 +1217,6 @@ static int ncm_unwrap_ntb(struct gether 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) { @@ -1244,7 +1243,6 @@ static int ncm_unwrap_ntb(struct gether }
ndp_index = get_ncm(&tmp, opts->ndp_index); - ndp_after_header = false;
/* Run through all the NDP's in the NTB */ do { @@ -1260,8 +1258,6 @@ static int ncm_unwrap_ntb(struct gether ndp_index); goto err; } - if (ndp_index == opts->nth_size) - ndp_after_header = true;
/* * walk through NDP @@ -1340,37 +1336,13 @@ 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 @@ -1387,6 +1359,8 @@ 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);