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Bryam Vargas b2f596f00d Input: synaptics-rmi4 - bound the F54 report size to the allocated buffer 
commit 49c5adc2b7 upstream.

rmi_f54_work() reads a diagnostics report from the device into
f54->report_data, sizing the transfer with rmi_f54_get_report_size():

	report_size = rmi_f54_get_report_size(f54);
	...
	for (i = 0; i < report_size; i += F54_REPORT_DATA_SIZE) {
		int size = min(F54_REPORT_DATA_SIZE, report_size - i);
		...
		rmi_read_block(.., f54->report_data + i, size);
	}

report_data is allocated once at probe from F54's own electrode counts
(array3_size(f54->num_tx_electrodes, f54->num_rx_electrodes, sizeof(u16))),
but rmi_f54_get_report_size() computes the size from
drv_data->num_*_electrodes when those are set, i.e. from the F55
function's electrode counts. Both counts come straight from device
queries (F54 and F55 each report up to 255 electrodes) and nothing
constrains the F55 counts to the F54 ones.

A malicious or malfunctioning RMI4 device that reports larger F55
electrode counts than its F54 counts makes report_size exceed the
allocation, so the read loop writes past report_data (and the V4L2
dequeue memcpy() then reads past it). On conforming hardware the F55
configured electrodes are a subset of the F54 physical electrodes, so
report_size never exceeds the buffer and well-behaved devices are
unaffected.

Record the allocation size and reject a report that does not fit,
mirroring the existing zero-size check.

Fixes: c762cc68b6 ("Input: synaptics-rmi4 - propagate correct number of rx and tx electrodes to F54")
Cc: stable@vger.kernel.org
Signed-off-by: Bryam Vargas <hexlabsecurity@proton.me>
Assisted-by: Antigravity:gemini-3.5-flash
Link: https://patch.msgid.link/20260626051802.4033172-3-dmitry.torokhov@gmail.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2026-08-23 14:17:15 +02:00
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README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.