Bug 2532179 (CVE-2026-89628)

Summary: CVE-2026-89628 kernel: HID: picolcd: clamp eeprom debugfs read to bytes actually received
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Human Interface Device (HID) picolcd driver in the Linux kernel. A local attacker with root privileges, by using a specially crafted or spoofed picoLCD device, could exploit an out-of-bounds read vulnerability in the picolcd_debug_eeprom_read() function. This flaw occurs because the function trusts a device-supplied length without proper validation against the actual received data size. Successful exploitation could lead to the disclosure of sensitive information from adjacent kernel memory to userspace.
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Description OSIDB Bzimport 2026-09-11 21:08:59 UTC 
In the Linux kernel, the following vulnerability has been resolved:

HID: picolcd: clamp eeprom debugfs read to bytes actually received

picolcd_debug_eeprom_read() trusts resp->raw_data[2] -- a length byte
supplied by the device in its REPORT_EE_DATA reply -- clamped only to
the caller's read() count:

	ret = resp->raw_data[2];
	if (ret > s)
		ret = s;
	if (copy_to_user(u, resp->raw_data+3, ret))

It never checks resp->raw_size, the number of bytes picolcd_raw_event()
actually copied into the 64-byte raw_data[] of the kmalloc'd struct
picolcd_pending. A device (or a spoofed picoLCD) returning a length byte
of 0xff, read with a count >= 255, makes copy_to_user() read past
raw_data[] into adjacent slab memory and return it to userspace through
the debugfs "eeprom" file:

	BUG: KASAN: slab-out-of-bounds in _copy_to_user
	Read of size 255 ... picolcd_debug_eeprom_read+0x214/0x2f0 [hid_picolcd]

The debug-dump path in the same file already validates the device length
byte against the received size before trusting it; this read does not.
The file is created S_IRUSR (root-only) and a crafted device is needed,
so it is neither unprivileged- nor remotely-triggerable.

Clamp the copy length to resp->raw_size - 3 (the payload actually
received, minus the 3-byte header), floored at 0 for short replies.
Comment 1 Keith Grant 2026-09-18 19:36:18 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89628.mbox