f2e19b3659
The transaction buffer is allocated by using the size of the packet buf,
and subtracting two which seem intended to remove the two tags which are
not present in the target structure. This calculation leads to under
counting memory because of differences between the packet contents and the
target structure. The aid_len field is a u8 in the packet, but a u32 in
the structure, resulting in at least 3 bytes always being under counted.
Further, the aid data is a variable length field in the packet, but fixed
in the structure, so if this field is less than the max, the difference is
added to the under counting.
The last validation check for transaction->params_len is also incorrect
since it employs the same accounting error.
To fix, perform validation checks progressively to safely reach the
next field, to determine the size of both buffers and verify both tags.
Once all validation checks pass, allocate the buffer and copy the data.
This eliminates freeing memory on the error path, as those checks are
moved ahead of memory allocation.
Fixes: 26fc6c7f02cb ("NFC: st21nfca: Add HCI transaction event support")
Fixes: 4fbcc1a4cb20 ("nfc: st21nfca: Fix potential buffer overflows in EVT_TRANSACTION")
Cc: stable@vger.kernel.org
Signed-off-by: Martin Faltesek <mfaltesek@google.com>
Reviewed-by: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.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.