In the Linux kernel, the following vulnerability has been resolved:usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBsIt is observed sometimes when tethering is used over NCM with Windows 11as host, at some instances, the gadget_giveback has one byte appended atthe end of a proper NTB. When the NTB is parsed, unwrap call looks forany leftover bytes in SKB provided by u_ether and if there are any pendingbytes, it treats them as a separate NTB and parses it. But in case thesecond NTB (as per unwrap call) is faulty/corrupt, all the datagrams thatwere parsed properly in the first NTB and saved in rx_list are dropped.Adding a few custom traces showed the following:[002] d..1  7828.532866: dwc3_gadget_giveback: ep1out:req 000000003868811a length 1025/16384 zsI ==> 0[002] d..1  7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb toprocess: 1025[002] d..1  7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342[002] d..1  7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb seq: 0xce67[002] d..1  7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x400[002] d..1  7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb ndp_len: 0x10[002] d..1  7828.532869: ncm_unwrap_ntb: K: Parsed NTB with 1 framesIn this case, the giveback is of 1025 bytes and block length is 1024.The rest 1 byte (which is 0x00) won't be parsed resulting in drop ofall datagrams in rx_list.Same is case with packets of size 2048:[002] d..1  7828.557948: dwc3_gadget_giveback: ep1out:req 0000000011dfd96e length 2049/16384 zsI ==> 0[002] d..1  7828.557949: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342[002] d..1  7828.557950: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x800Lecroy shows one byte coming in extra confirming that the byte is comingin from PC: Transfer 2959 - Bytes Transferred(1025)  Timestamp((18.524 843 590) - Transaction 8391 - Data(1025 bytes) Timestamp(18.524 843 590) --- Packet 4063861       Data(1024 bytes)       Duration(2.117us) Idle(14.700ns) Timestamp(18.524 843 590) --- Packet 4063863       Data(1 byte)       Duration(66.160ns) Time(282.000ns) Timestamp(18.524 845 722)According to Windows driver, no ZLP is needed if wBlockLength is non-zero,because the non-zero wBlockLength has already told the function side thesize of transfer to be expected. However, there are in-market NCM devicesthat rely on ZLP as long as the wBlockLength is multiple of wMaxPacketSize.To deal with such devices, it pads an extra 0 at end so the transfer is nolonger multiple of wMaxPacketSize.
CWE-476 NULL Pointer Dereference