Bug 2422810 (CVE-2025-68308)

Summary: CVE-2025-68308 kernel: Linux kernel: Denial of Service in kvaser_usb CAN driver due to infinite loop
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel, specifically within the kvaser_usb CAN driver. This vulnerability allows a local user to trigger an infinite loop in the command parsing logic. This occurs when zero-length commands, used for data alignment, are encountered precisely on a packet boundary, causing the buffer position to not advance. The primary consequence of this flaw is a Denial of Service (DoS) to the system.
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Description OSIDB Bzimport 2025-12-16 16:03:16 UTC 
In the Linux kernel, the following vulnerability has been resolved:

can: kvaser_usb: leaf: Fix potential infinite loop in command parsers

The `kvaser_usb_leaf_wait_cmd()` and `kvaser_usb_leaf_read_bulk_callback`
functions contain logic to zero-length commands. These commands are used
to align data to the USB endpoint's wMaxPacketSize boundary.

The driver attempts to skip these placeholders by aligning the buffer
position `pos` to the next packet boundary using `round_up()` function.

However, if zero-length command is found exactly on a packet boundary
(i.e., `pos` is a multiple of wMaxPacketSize, including 0), `round_up`
function will return the unchanged value of `pos`. This prevents `pos`
to be increased, causing an infinite loop in the parsing logic.

This patch fixes this in the function by using `pos + 1` instead.
This ensures that even if `pos` is on a boundary, the calculation is
based on `pos + 1`, forcing `round_up()` to always return the next
aligned boundary.
Comment 1 Alexander B 2025-12-16 19:05:10 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025121645-CVE-2025-68308-5dc4@gregkh/T