From: Zhang Cen <rollkingzzc@gmail.com> stable inclusion from stable-v6.6.143 commit be50533fe7068e86eb7adb81988e6d6a3f6dfe53 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16230 CVE: CVE-2026-63902 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 9f9bfc80c67f35a275820da7e83a35dface08281 upstream. cypress_read_int_callback() parses the interrupt-in buffer according to the selected Cypress packet format. Format 1 has a two-byte status/count header and format 2 has a one-byte combined status/count header. The usb-serial core sizes the interrupt-in buffer from the endpoint descriptor's wMaxPacketSize, and successful interrupt transfers can complete short when URB_SHORT_NOT_OK is not set. Check that the completed packet contains the selected header before reading it. Malformed short reports are ignored and the interrupt URB is resubmitted through the existing retry path, preventing out-of-bounds header-byte reads. KASAN report as below: KASAN slab-out-of-bounds in cypress_read_int_callback+0x240/0x7f0 Read of size 1 Call trace: cypress_read_int_callback() (drivers/usb/serial/cypress_m8.c:1009) __usb_hcd_giveback_urb() dummy_timer() Fixes: 3416eaa1f8f8 ("USB: cypress_m8: Packet format is separate from characteristic size") Assisted-by: Codex:gpt-5.5 Signed-off-by: Zhang Cen <rollkingzzc@gmail.com> Fixes: 3416eaa1f8f8 ("USB: cypress_m8: Packet format is separate from characteristic size") Cc: stable@vger.kernel.org # 2.6.26 [ johan: use constants in header length sanity checks ] Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- drivers/usb/serial/cypress_m8.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/usb/serial/cypress_m8.c b/drivers/usb/serial/cypress_m8.c index 1e0c028c5ec9..4c625e77da3a 100644 --- a/drivers/usb/serial/cypress_m8.c +++ b/drivers/usb/serial/cypress_m8.c @@ -1020,8 +1020,8 @@ static void cypress_read_int_callback(struct urb *urb) char tty_flag = TTY_NORMAL; int bytes = 0; int result; - int i = 0; int status = urb->status; + int i; switch (status) { case 0: /* success */ @@ -1059,22 +1059,32 @@ static void cypress_read_int_callback(struct urb *urb) spin_lock_irqsave(&priv->lock, flags); result = urb->actual_length; + i = 0; switch (priv->pkt_fmt) { default: case packet_format_1: /* This is for the CY7C64013... */ + if (result < 2) + break; priv->current_status = data[0] & 0xF8; bytes = data[1] + 2; i = 2; break; case packet_format_2: /* This is for the CY7C63743... */ + if (result < 1) + break; priv->current_status = data[0] & 0xF8; bytes = (data[0] & 0x07) + 1; i = 1; break; } spin_unlock_irqrestore(&priv->lock, flags); + if (i == 0) { + dev_dbg(dev, "%s - short packet received: %d bytes\n", + __func__, result); + goto continue_read; + } if (result < bytes) { dev_dbg(dev, "%s - wrong packet size - received %d bytes but packet said %d bytes\n", -- 2.34.1