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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=G+KJgNk5 c=1 sm=1 tr=0 ts=6aa8cf42 cx=c_pps a=Oh5Dbbf/trHjhBongsHeRQ==:117 a=ebQaAufLtzKgtO4u2lSP0Q==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=gowsoOTTUOVcmtlkKump:22 a=VwQbUJbxAAAA:8 a=pGLkceISAAAA:8 a=HSZgmaD_RsK9m5tnku4A:9 a=QEXdDO2ut3YA:10 a=_Vgx9l1VpLgwpw_dHYaR:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTE1MDA2NiBTYWx0ZWRfXwx9ihQwx0q68 I8BxertkAbzjc0MwVL0q8mQSCMp6oY98ArhDCZbBILx/0bqSK16v3Zxmez20JA0v8ZybpFstK8z 118V7lF6hFxCG9oXix8N3ttText2ACl8eEX3um/Wkuc3ssBGx2mIP5I/9ZM38W2Pyc9Dil1kh3e 7ebKtq9Mq5B2Xp3bfIsR4+Rzz8MiWg7GX1zCvkyly/foKi9rVmd6rQ5kcXySt88tb/pDNhXIhTP G2m6kCNyLz+t8Tvw5dPrJtNnUZCGaG2oAmZSJTCHjguHkCoceWWC+7tfogb95vtrk1+q8N5w37m 07ICa1KMRp7BohmOUdUncjbU9WX2yTYeyx4x3UBfCh0hwGJe6H4jbozAUdCiXHdLC3GjFYknmUH nlFtUVPswkabO/rsT/922PljLNhqUL5Zx0/ZWeAoUMqYwZ9S7jphTfvCCoWu9RFS+HzvPB/H82a RH3XK2orubN8c8bhdrg== X-Proofpoint-GUID: pc7X0NRSIIrf9cF__zZ6EsKl0XJVk2P3 X-Proofpoint-ORIG-GUID: pc7X0NRSIIrf9cF__zZ6EsKl0XJVk2P3 X-Proofpoint-Spam-Info: AW1haW4tMjYwOTE1MDA2NiBTYWx0ZWRfX9FbFdmgDOB4U UGdlMLRjKRwptfU0pTHrOrwU09g9NQNMCJLQ3UvuLimptRbX1/PIORZC6zaAR3ofHzPHihSNRmJ 3co23G8QUOfeU8YXqtuJ3n1TMA7tAyU= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-15_01,2026-09-14_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 impostorscore=0 malwarescore=0 clxscore=1015 lowpriorityscore=0 phishscore=0 adultscore=0 priorityscore=1501 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609150066 On 9/15/2026 9:41 AM, Aldo Ariel Panzardo wrote: > The next-NDP pointers form a chain supplied by the USB host. A cyclic > chain therefore makes the receive path loop indefinitely and repeatedly > allocate datagram skbs. > Is this an issue with NTB creation on host side ? (seems like it). If so, can you update commit message with an example packet details indicating the same (or a walkthrough of a packet with such headers indicating a cyclic chain). Regards, Krishna, > Prewalk the chain using only bounded header reads before parsing any > NDP. NDP offsets must be four-byte aligned, so following more than > block_len / 4 valid offsets proves that the chain contains a cycle. > This terminates cyclic chains without imposing an arbitrary limit on > valid NTBs or allocating skbs before the chain is known to terminate. > > Fixes: 370af734dfaf ("usb: gadget: NCM: RX function support multiple NDPs") > Cc: stable@vger.kernel.org > Signed-off-by: Aldo Ariel Panzardo > --- > drivers/usb/gadget/function/f_ncm.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/drivers/usb/gadget/function/f_ncm.c b/drivers/usb/gadget/function/f_ncm.c > index 64eabda2f5..085aea142f 100644 > --- a/drivers/usb/gadget/function/f_ncm.c > +++ b/drivers/usb/gadget/function/f_ncm.c > @@ -1175,6 +1175,7 @@ static int ncm_unwrap_ntb(struct gether *port, > unsigned dg_len, dg_len2; > unsigned ndp_len; > unsigned block_len; > + unsigned int ndp_count, next_ndp_index; > struct sk_buff *skb2; > int ret = -EINVAL; > unsigned ntb_max = le32_to_cpu(ntb_parameters.dwNtbOutMaxSize); > @@ -1224,6 +1225,30 @@ static int ncm_unwrap_ntb(struct gether *port, > } > > ndp_index = get_ncm(&tmp, opts->ndp_index); > + next_ndp_index = ndp_index; > + ndp_count = 0; > + > + /* Validate the NDP chain before allocating datagram skbs. */ > + while (next_ndp_index) { > + if (next_ndp_index % 4 || > + next_ndp_index < opts->nth_size || > + next_ndp_index > block_len - opts->ndp_size) { > + INFO(port->func.config->cdev, "Bad index: %#X\n", > + next_ndp_index); > + goto err; > + } > + > + /* More aligned offsets than fit in the NTB imply a cycle. */ > + if (++ndp_count > block_len / 4) { > + INFO(port->func.config->cdev, "NDP chain cycle\n"); > + goto err; > + } > + > + tmp = (__le16 *)(ntb_ptr + next_ndp_index); > + tmp += 3; /* skip the signature and length */ > + tmp += opts->reserved1; > + next_ndp_index = get_ncm(&tmp, opts->next_ndp_index); > + } > > /* Run through all the NDP's in the NTB */ > do {