From e563b01208f4d1f609bcab13333b6c0e24ce6a01 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Wed, 12 Feb 2025 19:15:15 +0100 Subject: usb: cdc-acm: Check control transfer buffer size before access If the first fragment is shorter than struct usb_cdc_notification, we can't calculate an expected_size. Log an error and discard the notification instead of reading lengths from memory outside the received data, which can lead to memory corruption when the expected_size decreases between fragments, causing `expected_size - acm->nb_index` to wrap. This issue has been present since the beginning of git history; however, it only leads to memory corruption since commit ea2583529cd1 ("cdc-acm: reassemble fragmented notifications"). A mitigating factor is that acm_ctrl_irq() can only execute after userspace has opened /dev/ttyACM*; but if ModemManager is running, ModemManager will do that automatically depending on the USB device's vendor/product IDs and its other interfaces. Cc: stable Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Jann Horn Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'drivers/usb/class/cdc-acm.c') diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 6b37d1c47fce..39c7db7bcd21 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -371,7 +371,7 @@ static void acm_process_notification(struct acm *acm, unsigned char *buf) static void acm_ctrl_irq(struct urb *urb) { struct acm *acm = urb->context; - struct usb_cdc_notification *dr = urb->transfer_buffer; + struct usb_cdc_notification *dr; unsigned int current_size = urb->actual_length; unsigned int expected_size, copy_size, alloc_size; int retval; @@ -398,9 +398,20 @@ static void acm_ctrl_irq(struct urb *urb) usb_mark_last_busy(acm->dev); - if (acm->nb_index) + if (acm->nb_index == 0) { + /* + * The first chunk of a message must contain at least the + * notification header with the length field, otherwise we + * can't get an expected_size. + */ + if (current_size < sizeof(struct usb_cdc_notification)) { + dev_dbg(&acm->control->dev, "urb too short\n"); + goto exit; + } + dr = urb->transfer_buffer; + } else { dr = (struct usb_cdc_notification *)acm->notification_buffer; - + } /* size = notification-header + (optional) data */ expected_size = sizeof(struct usb_cdc_notification) + le16_to_cpu(dr->wLength); -- cgit v1.2.3 From 12e712964f41d05ae034989892de445781c46730 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Wed, 12 Feb 2025 19:15:16 +0100 Subject: usb: cdc-acm: Fix handling of oversized fragments If we receive an initial fragment of size 8 bytes which specifies a wLength of 1 byte (so the reassembled message is supposed to be 9 bytes long), and we then receive a second fragment of size 9 bytes (which is not supposed to happen), we currently wrongly bypass the fragment reassembly code but still pass the pointer to the acm->notification_buffer to acm_process_notification(). Make this less wrong by always going through fragment reassembly when we expect more fragments. Before this patch, receiving an overlong fragment could lead to `newctrl` in acm_process_notification() being uninitialized data (instead of data coming from the device). Cc: stable Fixes: ea2583529cd1 ("cdc-acm: reassemble fragmented notifications") Signed-off-by: Jann Horn Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/usb/class/cdc-acm.c') diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 39c7db7bcd21..c70f34993623 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -416,7 +416,7 @@ static void acm_ctrl_irq(struct urb *urb) expected_size = sizeof(struct usb_cdc_notification) + le16_to_cpu(dr->wLength); - if (current_size < expected_size) { + if (acm->nb_index != 0 || current_size < expected_size) { /* notification is transmitted fragmented, reassemble */ if (acm->nb_size < expected_size) { u8 *new_buffer; -- cgit v1.2.3 From 7284922f3e4fa285dff1b8bb593aa9a0b8458f30 Mon Sep 17 00:00:00 2001 From: Marek Vasut Date: Sun, 9 Feb 2025 15:56:11 +0100 Subject: USB: cdc-acm: Fill in Renesas R-Car D3 USB Download mode quirk Add Renesas R-Car D3 USB Download mode quirk and update comments on all the other Renesas R-Car USB Download mode quirks to discern them from each other. This follows R-Car Series, 3rd Generation reference manual Rev.2.00 chapter 19.2.8 USB download mode . Fixes: 6d853c9e4104 ("usb: cdc-acm: Add DISABLE_ECHO for Renesas USB Download mode") Cc: stable Signed-off-by: Marek Vasut Reviewed-by: Geert Uytterhoeven Link: https://lore.kernel.org/r/20250209145708.106914-1-marek.vasut+renesas@mailbox.org Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'drivers/usb/class/cdc-acm.c') diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index c70f34993623..c2ecfa3c8349 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1738,13 +1738,16 @@ static const struct usb_device_id acm_ids[] = { { USB_DEVICE(0x0870, 0x0001), /* Metricom GS Modem */ .driver_info = NO_UNION_NORMAL, /* has no union descriptor */ }, - { USB_DEVICE(0x045b, 0x023c), /* Renesas USB Download mode */ + { USB_DEVICE(0x045b, 0x023c), /* Renesas R-Car H3 USB Download mode */ .driver_info = DISABLE_ECHO, /* Don't echo banner */ }, - { USB_DEVICE(0x045b, 0x0248), /* Renesas USB Download mode */ + { USB_DEVICE(0x045b, 0x0247), /* Renesas R-Car D3 USB Download mode */ .driver_info = DISABLE_ECHO, /* Don't echo banner */ }, - { USB_DEVICE(0x045b, 0x024D), /* Renesas USB Download mode */ + { USB_DEVICE(0x045b, 0x0248), /* Renesas R-Car M3-N USB Download mode */ + .driver_info = DISABLE_ECHO, /* Don't echo banner */ + }, + { USB_DEVICE(0x045b, 0x024D), /* Renesas R-Car E3 USB Download mode */ .driver_info = DISABLE_ECHO, /* Don't echo banner */ }, { USB_DEVICE(0x0e8d, 0x0003), /* FIREFLY, MediaTek Inc; andrey.arapov@gmail.com */ -- cgit v1.2.3