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9cfc586847
commit 496f9372eae14775e0524e83e952814691fe850a upstream.
In the ACPI debugger interface, the helper functions for read and write
operations use "int" as the length parameter data type. When a large
"size_t count" is passed from the file operations, this cast to "int"
results in truncation and a negative value due to signed integer
representation.
Logically, this negative number propagates to the min() calculation,
where it is selected over the positive buffer space value, leading to
unexpected behavior. Subsequently, when this negative value is used in
copy_to_user() or copy_from_user(), it is interpreted as a large positive
value due to the unsigned nature of the size parameter in these functions,
causing the copy operations to attempt handling sizes far beyond the
intended buffer limits.
Address the issue by:
- Changing the length parameters in acpi_aml_read_user() and
acpi_aml_write_user() from "int" to "size_t", aligning with the
expected unsigned size semantics.
- Updating return types and local variables in acpi_aml_read() and
acpi_aml_write() to "ssize_t" for consistency with kernel file
operation conventions.
- Using "size_t" for the "n" variable to ensure calculations remain
unsigned.
- Using min_t() for circ_count_to_end() and circ_space_to_end() to
ensure type-safe comparisons and prevent integer overflow.
Signed-off-by: Amir Mohammad Jahangirzad <a.jahangirzad@gmail.com>
Link: https://patch.msgid.link/20250923013113.20615-1-a.jahangirzad@gmail.com
[ rjw: Changelog tweaks, local variable definitions ordering adjustments ]
Fixes: 8cfb0cdf07 ("ACPI / debugger: Add IO interface to access debugger functionalities")
Cc: 4.5+ <stable@vger.kernel.org> # 4.5+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.