diff options
| author | Jann Horn <jannh@google.com> | 2025-02-12 19:15:16 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-02-21 14:01:32 +0100 |
| commit | a5b205ceefa5e4d62c63f50fa4ee923ce66fdba2 (patch) | |
| tree | 37425202afe87cf23574f9e4495caa16bd2f536a | |
| parent | f64079bef6a8a7823358c3f352ea29a617844636 (diff) | |
usb: cdc-acm: Fix handling of oversized fragments
commit 12e712964f41d05ae034989892de445781c46730 upstream.
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 <stable@kernel.org>
Fixes: ea2583529cd1 ("cdc-acm: reassemble fragmented notifications")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/usb/class/cdc-acm.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index c3a783e0d979..c2ecfa3c8349 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; |