Bug 2502381 (CVE-2026-63960) - CVE-2026-63960 kernel: usb: typec: wcove: don't write past struct pd_message in wcove_read_rx_buffer()
Summary: CVE-2026-63960 kernel: usb: typec: wcove: don't write past struct pd_message ...
Keywords:
Status: NEW
Alias: CVE-2026-63960
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
unspecified
unspecified
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-19 16:04 UTC by OSIDB Bzimport
Modified: 2026-07-21 22:53 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


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Description OSIDB Bzimport 2026-07-19 16:04:59 UTC
In the Linux kernel, the following vulnerability has been resolved:

usb: typec: wcove: don't write past struct pd_message in wcove_read_rx_buffer()

wcove_read_rx_buffer() copies the PD RX FIFO into the caller's
struct pd_message with

	for (i = 0; i < USBC_RXINFO_RXBYTES(info); i++)
		regmap_read(wcove->regmap, USBC_RX_DATA + i, msg + i);

which has two problems:

USBC_RXINFO_RXBYTES() is a 5-bit field (max 31) while struct pd_message
is 30 bytes (__le16 header + __le32 payload[PD_MAX_PAYLOAD], packed).
The byte count latched in RXINFO is the number of bytes the port partner
put on the wire, so a malicious partner that transmits a 31-byte frame
can drive the loop one byte past the destination if the WCOVE BMC
receiver does not enforce the PD object-count limit in hardware. The
existing FIXME flagged this as unverified.

Independently, regmap_read() takes an unsigned int * and stores a full
unsigned int at the destination. Passing the byte pointer msg + i means
each iteration writes four bytes; the high three are zero (val_bits is
8) and are normally overwritten by the next iteration, but the final
iteration's high bytes are not. With RXBYTES == 30 the i == 29 iteration
already writes three zero bytes past msg, which sits on the IRQ thread's
stack in wcove_typec_irq().

Clamp the loop to sizeof(struct pd_message) and read each register into
a local before storing only its low byte, so the copy can never exceed
the destination regardless of what RXINFO reports.


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