0836275df4
UBSAN: array-index-out-of-bounds in drivers/block/floppy.c:1521:45
index 16 is out of range for type 'unsigned char [16]'
Call Trace:
...
setup_rw_floppy+0x5c3/0x7f0
floppy_ready+0x2be/0x13b0
process_one_work+0x2c1/0x5d0
worker_thread+0x56/0x5e0
kthread+0x122/0x170
ret_from_fork+0x35/0x40
From include/uapi/linux/fd.h:
struct floppy_raw_cmd {
...
unsigned char cmd_count;
unsigned char cmd[16];
unsigned char reply_count;
unsigned char reply[16];
...
}
This out-of-bounds access is intentional. The command in struct
floppy_raw_cmd may take up the space initially intended for the reply
and the reply count. It is needed for long 82078 commands such as
RESTORE, which takes 17 command bytes. Initial cmd size is not enough
and since struct setup_rw_floppy is a part of uapi we check that
cmd_count is in [0:16+1+16] in raw_cmd_copyin().
The patch adds union with original cmd,reply_count,reply fields and
fullcmd field of equivalent size. The cmd accesses are turned to
fullcmd where appropriate to suppress UBSAN warning.
Link: https://lore.kernel.org/r/20200501134416.72248-5-efremov@linux.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Denis Efremov <efremov@linux.com>
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.