kernel/linux.git/drivers/usb/serial, branch v6.6.150

USB: serial: option: add TDTECH MT5710-CN

2026-08-03T09:15:17+00:00

commit 55645e4f3c6022ffb160ad3617d2b624eaa38501 upstream. Add support for the TDTECH MT5710-CN (5G redcap) module based on the Huawei HiSilicon Balong chip. T: Bus=01 Lev=02 Prnt=02 Port=00 Cnt=01 Dev#= 3 Spd=480 MxCh= 0 D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=3466 ProdID=3301 Rev=ff.ff S: Manufacturer=TD Tech Ltd. S: Product=TDTECH MT571X S: SerialNumber=0123456789ABCDEF C:* #Ifs= 6 Cfg#= 1 Atr=c0 MxPwr= 0mA A: FirstIf#= 0 IfCount= 2 Cls=02(comm.) Sub=0d Prot=00 I:* If#= 0 Alt= 0 #EPs= 1 Cls=02(comm.) Sub=0d Prot=00 Driver=cdc_ncm E: Ad=82(I) Atr=03(Int.) MxPS= 16 Ivl=32ms I: If#= 1 Alt= 0 #EPs= 0 Cls=0a(data ) Sub=00 Prot=01 Driver=cdc_ncm I:* If#= 1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=01 Driver=cdc_ncm E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I:* If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=13 Driver=option E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I:* If#= 3 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=12 Driver=option E: Ad=84(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I:* If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=1c Driver=option E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms I:* If#= 5 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=06 Prot=14 Driver=option E: Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms Interface: ECM / NCM + DIAG + AT + SERIAL + GPS Signed-off-by: Chukun Pan Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: keyspan_pda: fix data loss on receive throttling

2026-08-03T09:15:17+00:00

commit 42a97c0480f96a2977e6d51ce512adc780f1ef5d upstream. Killing the interrupt-in urb when the line disciple requests throttling may lead to data loss if an ongoing transfer is cancelled. Instead set a flag to prevent the completion handler from resubmitting the urb until the port is unthrottled. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: io_edgeport: cap received transmit credits

2026-08-03T09:15:17+00:00

commit faaddd811c5099f11a5f52e68a6b31a5898cda4f upstream. The interrupt-status packet reports transmit credits returned by the device. edge_interrupt_callback() adds the 16-bit value to txCredits without checking maxTxCredits. edge_write() uses txCredits minus the software FIFO count as the amount of data that fits. Since the FIFO is allocated with maxTxCredits bytes, txCredits exceeding maxTxCredits can cause OOB write in ring buffer. Cap accumulated credits at maxTxCredits. Conforming devices should never hit the cap. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Assisted-by: Codex:GPT-5 Signed-off-by: Sunho Park Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: ftdi_sio: add support for E+H FXA291

2026-08-03T09:15:16+00:00

commit fad0fd120e29041b3e6cdf41bb12e3184fb524a2 upstream. The Commubox FXA291 by Endress+Hauser AG is a USB serial converter based on FT232B which is used to communicate with field devices. It enumerates using the FTDI vendor ID and a custom PID. usb 1-9: New USB device found, idVendor=0403, idProduct=e510, bcdDevice= 4.00 usb 1-9: New USB device strings: Mfr=1, Product=2, SerialNumber=0 usb 1-9: Product: FXA291 usb 1-9: Manufacturer: Endress+Hauser usb 1-9: SerialNumber: 00000000 ftdi_sio 1-9:1.0: FTDI USB Serial Device converter detected usb 1-9: Detected FT232B usb 1-9: FTDI USB Serial Device converter now attached to ttyUSB0 Signed-off-by: Tim Pambor Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: digi_acceleport: fix write buffer corruption

2026-07-24T14:02:50+00:00

commit 24ca1fea8f2753bf33e1d458ec1ae5d9b7796a65 upstream. The digi_write_inb_command() is supposed to wait for the write urb to become available or return an error, but instead it updates the transfer buffer and tries to resubmit the urb on timeout. To make things worse, for commands like break control where no timeout is used, the driver would corrupt the urb immediately due to a broken jiffies comparison (on 32-bit machines this takes five minutes of uptime to trigger due to INITIAL_JIFFIES). Fix this by adding the missing return on timeout and waiting indefinitely when no timeout has been specified as intended. This issue was (sort of) flagged by Sashiko when reviewing an unrelated change to the driver. Link: https://sashiko.dev/#/patchset/20260610132232.356139-1-johan%40kernel.org?part=11 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: digi_acceleport: fix hard lockup on disconnect

2026-07-24T14:02:50+00:00

commit 5c1ea24b53bf3bfb859f0a05573997487975da23 upstream. If submitting the OOB write urb fails persistently (e.g if the device is being disconnected) the driver would loop indefinitely with interrupts disabled. Check for urb submission errors when sending OOB commands to avoid hanging if, for example, open(), set_termios() or close() races with a physical disconnect. This is issue was flagged by Sashiko when reviewing an unrelated change to the driver. Link: https://sashiko.dev/#/patchset/20260610132232.356139-1-johan%40kernel.org?part=1 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Reviewed-by: Greg Kroah-Hartman Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: digi_acceleport: fix broken rx after throttle

2026-07-24T14:02:50+00:00

commit 83a3dfc018943b05b6daf3a6f891833e1aabfa1f upstream. If the port is closed while throttled, the read urb is never resubmitted and the port will not receive any further data until the device is reconnected (or the driver is rebound). Clear the throttle flags and submit the urb if needed when opening the port. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: option: add Telit Cinterion FE990D50 compositions

2026-07-24T14:02:50+00:00

commit b33ab1dd80f5c1742f49eb6ec7b337c5ffcf3d32 upstream. Add support for Telit Cinterion FE990D50 compositions: 0x990: RNDIS + tty (AT/NMEA) + tty (AT) + tty (AT) + tty (AT) + tty (diag) + ADPL + adb T: Bus=01 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 3 Spd=480 MxCh= 0 D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1bc7 ProdID=0990 Rev=06.06 S: Manufacturer=Telit Cinterion S: Product=FE990 S: SerialNumber=90b6a3ed C: #Ifs=10 Cfg#= 1 Atr=e0 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 1 Cls=ef(misc ) Sub=04 Prot=01 Driver=rndis_host E: Ad=82(I) Atr=03(Int.) MxPS= 8 Ivl=32ms I: If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=rndis_host E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=60 Driver=option E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=84(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=86(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=88(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 5 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=89(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8a(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 6 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=30 Driver=option E: Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8b(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 7 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=80 Driver=(none) E: Ad=8c(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 8 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=70 Driver=(none) E: Ad=8d(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 9 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none) E: Ad=07(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8e(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms 0x991: rmnet + tty (AT/NMEA) + tty (AT) + tty (AT) + tty (AT) + tty (diag) + ADPL + adb T: Bus=01 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 9 Spd=480 MxCh= 0 D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1bc7 ProdID=0991 Rev=06.06 S: Manufacturer=Telit Cinterion S: Product=FE990 S: SerialNumber=90b6a3ed C: #Ifs= 9 Cfg#= 1 Atr=e0 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=50 Driver=(none) E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=82(I) Atr=03(Int.) MxPS= 8 Ivl=32ms I: If#= 1 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=60 Driver=option E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=84(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=86(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=88(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=89(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8a(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 5 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=30 Driver=option E: Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8b(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 6 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=80 Driver=(none) E: Ad=8c(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 7 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=70 Driver=(none) E: Ad=8d(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 8 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none) E: Ad=07(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8e(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms 0x992: MBIM + tty (AT/NMEA) + tty (AT) + tty (AT) + tty (AT) + tty (diag) + ADPL + adb T: Bus=01 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 12 Spd=480 MxCh= 0 D: Ver= 2.10 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=1bc7 ProdID=0992 Rev=06.06 S: Manufacturer=Telit Cinterion S: Product=FE990 S: SerialNumber=90b6a3ed C: #Ifs=10 Cfg#= 1 Atr=e0 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=0e Prot=00 Driver=cdc_mbim E: Ad=82(I) Atr=03(Int.) MxPS= 64 Ivl=32ms I: If#= 1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=02 Driver=cdc_mbim E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=60 Driver=option E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=84(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=86(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=88(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 5 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=89(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8a(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 6 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=30 Driver=option E: Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8b(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 7 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=80 Driver=(none) E: Ad=8c(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 8 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=70 Driver=(none) E: Ad=8d(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 9 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none) E: Ad=07(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8e(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms 0x993: ECM + tty (AT/NMEA) + tty (AT) + tty (AT) + tty (AT) + tty (diag) + ADPL + adb T: Bus=01 Lev=01 Prnt=01 Port=06 Cnt=03 Dev#= 15 Spd=480 MxCh= 0 D: Ver= 2.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1bc7 ProdID=0993 Rev=06.06 S: Manufacturer=Telit Cinterion S: Product=FE990 S: SerialNumber=90b6a3ed C: #Ifs=10 Cfg#= 1 Atr=e0 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 1 Cls=02(commc) Sub=06 Prot=00 Driver=cdc_ether E: Ad=82(I) Atr=03(Int.) MxPS= 16 Ivl=32ms I: If#= 1 Alt= 1 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=cdc_ether E: Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 2 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=60 Driver=option E: Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=83(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=84(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 3 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=03(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=85(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=86(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 4 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=04(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=87(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=88(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 5 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=ff Prot=40 Driver=option E: Ad=05(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=89(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8a(I) Atr=03(Int.) MxPS= 10 Ivl=32ms I: If#= 6 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=ff Prot=30 Driver=option E: Ad=06(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8b(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 7 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=80 Driver=(none) E: Ad=8c(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 8 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=70 Driver=(none) E: Ad=8d(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms I: If#= 9 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=42 Prot=01 Driver=(none) E: Ad=07(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms E: Ad=8e(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms Cc: stable@vger.kernel.org Signed-off-by: Fabio Porcedda Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: keyspan_pda: fix information leak

2026-07-24T14:02:50+00:00

commit 6bfc8d01ac4068eced509f8fc74d0cd205e4dcec upstream. The write() callback is supposed to return the number of characters accepted or a negative errno. Since the addition of write fifo support the keyspan_pda implementation will however return the number characters submitted to the device if the write urb is not already in use. If this number is larger than the number of characters passed to write(), the line discipline continues writing data from beyond the tty write buffer. Fix the information leak by making sure that keyspan_pda_write_start() returns zero on success as intended. Fixes: 034e38e8f687 ("USB: serial: keyspan_pda: add write-fifo support") Cc: stable@vger.kernel.org # 5.11 Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman

USB: serial: kl5kusb105: fix bulk-out buffer overflow

2026-06-19T11:39:32+00:00

commit 96d47e40bf9db4a9efd5c8fb53287a508d165f14 upstream. klsi_105_prepare_write_buffer() is called by the generic write path with the bulk-out buffer and its size (bulk_out_size, 64 bytes). It stores a two-byte length header at the start of the buffer and copies the payload from the write fifo starting at buf + KLSI_HDR_LEN, but passes the full buffer size as the number of bytes to copy: count = kfifo_out_locked(&port->write_fifo, buf + KLSI_HDR_LEN, size, &port->lock); When the fifo holds at least size bytes, size bytes are copied starting two bytes into the size-byte buffer, writing KLSI_HDR_LEN bytes past its end. Copy at most size - KLSI_HDR_LEN bytes instead, leaving room for the header as safe_serial already does. Writing bulk_out_size or more bytes to the tty triggers a slab out-of-bounds write, observed with KASAN by emulating the device with dummy_hcd and raw-gadget: BUG: KASAN: slab-out-of-bounds in kfifo_copy_out+0x83/0xc0 Write of size 64 at addr ffff888112c62202 by task python3 kfifo_copy_out klsi_105_prepare_write_buffer [kl5kusb105] usb_serial_generic_write_start [usbserial] Allocated by task 139: usb_serial_probe [usbserial] The buggy address is located 2 bytes inside of allocated 64-byte region The out-of-bounds write no longer occurs with this change applied. Fixes: 60b3013cdaf3 ("USB: kl5usb105: reimplement using generic framework") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: HyeongJun An Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman