From 2b74b0a04d3e9f9f08ff026e5663dce88ff94e52 Mon Sep 17 00:00:00 2001 From: Brooke Basile Date: Tue, 25 Aug 2020 09:07:27 -0400 Subject: USB: gadget: f_ncm: add bounds checks to ncm_unwrap_ntb() 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 Signed-off-by: Brooke Basile Acked-by: Felipe Balbi Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_ncm.c | 81 +++++++++++++++++++++++++++++++------ 1 file changed, 69 insertions(+), 12 deletions(-) (limited to 'drivers/usb/gadget/function/f_ncm.c') diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c index 1d900081b1f0..b4206b0dede5 100644 --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1181,12 +1181,15 @@ static int ncm_unwrap_ntb(struct gether *port, 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) { @@ -1205,25 +1208,37 @@ static int ncm_unwrap_ntb(struct gether *port, } 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"); @@ -1234,14 +1249,15 @@ static int ncm_unwrap_ntb(struct gether *port, 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; @@ -1258,8 +1274,21 @@ static int ncm_unwrap_ntb(struct gether *port, 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; @@ -1283,6 +1312,37 @@ static int ncm_unwrap_ntb(struct gether *port, 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 @@ -1299,9 +1359,6 @@ static int ncm_unwrap_ntb(struct gether *port, 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); -- cgit v1.2.3 From 2b405533c2560d7878199c57d95a39151351df72 Mon Sep 17 00:00:00 2001 From: Bryan O'Donoghue Date: Sun, 20 Sep 2020 18:01:58 +0100 Subject: USB: gadget: f_ncm: Fix NDP16 datagram validation 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 Cc: Brooke Basile Cc: stable Signed-off-by: Bryan O'Donoghue Link: https://lore.kernel.org/r/20200920170158.1217068-1-bryan.odonoghue@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/f_ncm.c | 30 ++---------------------------- 1 file changed, 2 insertions(+), 28 deletions(-) (limited to 'drivers/usb/gadget/function/f_ncm.c') diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c index b4206b0dede5..1f638759a953 100644 --- a/drivers/usb/gadget/function/f_ncm.c +++ b/drivers/usb/gadget/function/f_ncm.c @@ -1189,7 +1189,6 @@ static int ncm_unwrap_ntb(struct gether *port, 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) { @@ -1216,7 +1215,6 @@ static int ncm_unwrap_ntb(struct gether *port, } ndp_index = get_ncm(&tmp, opts->ndp_index); - ndp_after_header = false; /* Run through all the NDP's in the NTB */ do { @@ -1232,8 +1230,6 @@ static int ncm_unwrap_ntb(struct gether *port, ndp_index); goto err; } - if (ndp_index == opts->nth_size) - ndp_after_header = true; /* * walk through NDP @@ -1312,37 +1308,13 @@ static int ncm_unwrap_ntb(struct gether *port, 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 @@ -1359,6 +1331,8 @@ static int ncm_unwrap_ntb(struct gether *port, 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); -- cgit v1.2.3