In the Linux kernel, the following vulnerability has been resolved:
usb: misc: usbio: bound bulk IN response length to the received transfer
usbio_bulk_msg() copies bpkt_len = le16_to_cpu(bpkt->len) bytes out of
the bulk IN buffer (usbio->rxbuf, allocated with size usbio->rxbuf_len)
into the caller's buffer. bpkt_len is fully controlled by the device
and is only checked against ibuf_len; ibuf_len in turn is checked
against usbio->txbuf_len, not against rxbuf_len:
if ((obuf_len > (usbio->txbuf_len - sizeof(*bpkt))) ||
(ibuf_len > (usbio->txbuf_len - sizeof(*bpkt))))
return -EMSGSIZE;
txbuf_len and rxbuf_len are taken independently from the bulk OUT and
bulk IN endpoint wMaxPacketSize in usbio_probe(). A malicious or
malfunctioning device that advertises a large bulk OUT endpoint and a
small bulk IN endpoint (e.g. by claiming one of the quirk-free IDs such
as the Lattice NX33U, 0x2ac1:0x20cb) therefore makes ibuf_len, and
hence the device-supplied bpkt_len, exceed rxbuf_len. memcpy() then
reads up to txbuf_len - rxbuf_len bytes past the end of the rxbuf slab
object. The over-read bytes are handed back to the i2c layer and on to
user space through i2c-dev, disclosing adjacent slab memory; with KASAN
this is reported as a slab-out-of-bounds read.
The number of bytes actually received is already known: act equals the
URB actual_length and is bounded by rxbuf_len. Reject any response
that claims more payload than was received, mirroring the existing
"act < sizeof(*bpkt)" check just above.
The control path (usbio_ctrl_msg()) is not affected: it uses a single
buffer (ctrlbuf) for both directions, so its analogous copy can never
leave the allocation.
Found by code review. The out-of-bounds read was confirmed under
AddressSanitizer with a faithful userspace model of usbio_bulk_msg()'s
receive path (an rxbuf_len-sized buffer, the same act/ibuf_len/bpkt_len
checks and the memcpy). A USB raw-gadget + dummy_hcd reproducer is
also available.
SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines.
Exploitation none (no CISA value, KEV listing or exploit code on record) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). EchelonGraph holds no SSVC assessment of this CVE from CISA: none of these inputs is from Vulnrichment. EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA's BOD 26-04 default) · Technical impact total (CISA's BOD 26-04 default). Where an input reads “CISA's BOD 26-04 default”, no one has published it for this CVE, and CISA's implementation guidance says: “If “Automatable” and “Technical Impact” information items about a CVE ID are not available and the CVE ID is not in the KEV Catalog, CISA will treat its values as “no” and “total,” respectively, until CISA or a third party provides metadata about the CVE ID. CISA will always provide the Vulnrichment data for a CVE ID listed in the KEV Catalog.” Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it